Discovery of a user plane function that supports cellular IoT optimization

ABSTRACT

A network exposure function receives, from an application function, a first message requesting delivery of one or more Internet of Things (IoT) packets to a wireless device. The network exposure function sends, to a network repository function, a second message requesting a discovery of a user plane function that supports cellular IoT optimization. The network exposure function receives, from the network repository function, a third message comprising an identifier of the user plane function that supports the cellular IoT optimization. The network exposure function sends, to the user plane function, a fourth message requesting delivery of the one or more IoT packets to the wireless device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/366,670, filed Mar. 27, 2019, which claims the benefit of U.S.Provisional Application No. 62/650,631, filed Mar. 30, 2018, which ishereby incorporated by reference in its entirety.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Examples of several of the various embodiments of the present inventionare described herein with reference to the drawings.

FIG. 1 is a diagram of an example 5G system architecture as per anaspect of an embodiment of the present disclosure.

FIG. 2 is a diagram of an example 5G System architecture as per anaspect of an embodiment of the present disclosure.

FIG. 3 is a system diagram of an example wireless device and a networknode in a 5G system as per an aspect of an embodiment of the presentdisclosure.

FIG. 4 is a system diagram of an example wireless device as per anaspect of an embodiment of the present disclosure.

FIG. 5A and FIG. 5B depict two registration management state models inUE 100 and AMF 155 as per an aspect of embodiments of the presentdisclosure.

FIG. 6A and FIG. 6B depict two connection management state models in UE100 and AMF 155 as per an aspect of embodiments of the presentdisclosure.

FIG. 7 is diagram for classification and marking traffic as per anaspect of an embodiment of the present disclosure.

FIG. 8 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 9 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 10 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 11 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 12 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 13 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 14 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 15 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 16 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 17 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 18 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 19 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 20 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 21 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 22 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 23 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 24 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 25 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 26 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 27 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Example embodiments provide reliable Cellular Internet of Things (CIoT)related services for a wireless device. A Network Exposure Function(NEF) gets information of user plane network nodes and/or sessionmanagement function nodes that support a CIoT data transmission from anetwork repository function. The NEF configures network functions fortransmission of IoT data.

Example embodiments of the present invention enable implementation ofenhanced features and functionalities in, for example, 3GPP and/or 5Gsystems. Embodiments of the technology disclosed herein may be employedin communication systems, Cellular Internet of Things (IoT), MachineType Communication (MTC), and network slicing for communication systems.

The following acronyms are used throughout the present disclosure:

5G 5th generation mobile networks

5GC 5G Core Network

5GS 5G System

5G-AN 5G Access Network

5QI 5G QoS Indicator

AF Application Function

AMF Access and Mobility Management Function

AN Access Network

AS Application Server

CDR Charging Data Record

CCNF Common Control Network Functions

CIoT Cellular IoT

CN Core Network

CP Control Plane

DDN Downlink Data Notification

DL Downlink

DN Data Network

DNN Data Network Name

F-TEID Fully Qualified TEID

FQDN Fully Qualified Domain Name

GPSI Generic Public Subscription Identifier

GTP GPRS Tunneling Protocol

GUTI Globally Unique Temporary Identifier

IMSI International Mobile Subscriber Identity

IoT Internet of Things

LADN Local Area Data Network

LI Lawful Intercept

MEI Mobile Equipment Identifier

MICO Mobile Initiated Connection Only

MME Mobility Management Entity

MO Mobile Originated

MSISDN Mobile Subscriber ISDN

MT Mobile Terminating

MTC Machine Type Communication

N3IWF Non-3GPP InterWorking Function

NAI Network Access Identifier

NAS Non-Access Stratum

NB-IoT Narrow Band IoT

NEF Network Exposure Function

NF Network Function

NGAP Next Generation Application Protocol

NIMF Network IoT Messaging Function

NR New Radio

NRF Network Repository Function

NSI Network Slice Instance

NSSAI Network Slice Selection Assistance Information

NSSF Network Slice Selection Function

OCS Online Charging System

OFCS Offline Charging System

PCF Policy Control Function

PDU Packet/Protocol Data Unit

PEI Permanent Equipment Identifier

PLMN Public Land Mobile Network

RAN Radio Access Network

QFI QoS Flow Identity

RM Registration Management

S1-AP S1 Application Protocol

SBA Service Based Architecture

SEA Security Anchor Function

SCM Security Context Management

SCS Service Capability Server

SMF Session Management Function

SMSF SMS Function

S-NSSAI Single Network Slice Selection Assistance information

SUCI Served User Correlation ID

SUPI Subscriber Permanent Identifier

TEID Tunnel Endpoint Identifier

UE User Equipment

UL Uplink

UL CL Uplink Classifier

UPF User Plane Function

URRP UE Reachability Request Parameter

Throughout the present disclosure, UE, wireless device, and mobiledevice are used interchangeably. Throughout the present disclosure,CIoT, and MTC are used interchangeably.

Example FIG. 1 and FIG. 2 depict a 5G system comprising of accessnetworks and 5G core network. An example 5G access network may comprisean access network connecting to a 5G core network. An access network maycomprise an NG-RAN 105 and/or non-3GPP AN 165. An example 5G corenetwork may connect to one or more 5G access networks 5G-AN and/orNG-RANs. 5G core network may comprise functional elements or networkfunctions as in example FIG. 1 and example FIG. 2 where interfaces maybe employed for communication among the functional elements and/ornetwork elements.

In an example, a network function may be a processing function in anetwork, which may have a functional behavior and/or interfaces. Anetwork function may be implemented either as a network element on adedicated hardware, and/or a network node as depicted in FIG. 3 and FIG.4, or as a software instance running on a dedicated hardware and/orshared hardware, or as a virtualized function instantiated on anappropriate platform.

In an example, access and mobility management function, AMF 155, mayinclude the following functionalities (some of the AMF 155functionalities may be supported in a single instance of an AMF 155):termination of RAN 105 CP interface (N2), termination of NAS (N1), NASciphering and integrity protection, registration management, connectionmanagement, reachability management, mobility management, lawfulintercept (for AMF 155 events and interface to LI system), providetransport for session management, SM messages between UE 100 and SMF160, transparent proxy for routing SM messages, access authentication,access authorization, provide transport for SMS messages between UE 100and SMSF, security anchor function, SEA, interaction with the AUSF 150and the UE 100, receiving the intermediate key established as a resultof the UE 100 authentication process, security context management, SCM,that receives a key from the SEA that it uses to derive access networkspecific keys, and/or the like.

In an example, the AMF 155 may support non-3GPP access networks throughN2 interface with N3IWF 170, NAS signaling with a UE 100 over N3IWF 170,authentication of UEs connected over N3IWF 170, management of mobility,authentication, and separate security context state(s) of a UE 100connected via non-3GPP access 165 or connected via 3GPP access 105 andnon-3GPP access 165 simultaneously, support of a coordinated RM contextvalid over 3GPP access 105 and non 3GPP access 165, support of CMmanagement contexts for the UE 100 for connectivity over non-3GPPaccess, and/or the like.

In an example, an AMF 155 region may comprise one or multiple AMF 155sets. The AMF 155 set may comprise some AMF 155 that serve a given areaand/or network slice(s). In an example, multiple AMF 155 sets may be perAMF 155 region and/or network slice(s). Application identifier may be anidentifier that may be mapped to a specific application trafficdetection rule. Configured NSSAI may be an NSSAI that may be provisionedin a UE 100. DN 115 access identifier (DNAI), for a DNN, may be anidentifier of a user plane access to a DN 115. Initial registration maybe related to a UE 100 registration in RM-DEREGISTERED 500, 520 states.N2AP UE 100 association may be a logical per UE 100 association betweena 5G AN node and an AMF 155. N2AP UE-TNLA-binding may be a bindingbetween a N2AP UE 100 association and a specific transport networklayer, TNL association for a given UE 100.

In an example, session management function, SMF 160, may include one ormore of the following functionalities (one or more of the SMF 160functionalities may be supported in a single instance of a SMF 160):session management (e.g. session establishment, modify and release,including tunnel maintain between UPF 110 and AN 105 node), UE 100 IPaddress allocation & management (including optional authorization),selection and control of UP function(s), configuration of trafficsteering at UPF 110 to route traffic to proper destination, terminationof interfaces towards policy control functions, control part of policyenforcement and QoS, lawful intercept (for SM events and interface to LISystem), termination of SM parts of NAS messages, downlink datanotification, initiation of AN specific SM information, sent via AMF 155over N2 to (R)AN 105, determination of SSC mode of a session, roamingfunctionality, handling local enforcement to apply QoS SLAs (VPLMN),charging data collection and charging interface (VPLMN), lawfulintercept (in VPLMN for SM events and interface to LI System), supportfor interaction with external DN 115 for transport of signaling for PDUsession authorization/authentication by external DN 115, and/or thelike.

In an example, a user plane function, UPF 110, may include one or moreof the following functionalities (some of the UPF 110 functionalitiesmay be supported in a single instance of a UPF 110): anchor point forIntra-/Inter-RAT mobility (when applicable), external PDU session pointof interconnect to DN 115, packet routing & forwarding, packetinspection and user plane part of policy rule enforcement, lawfulintercept (UP collection), traffic usage reporting, uplink classifier tosupport routing traffic flows to a data network, branching point tosupport multi-homed PDU session(s), QoS handling for user plane, uplinktraffic verification (SDF to QoS flow mapping), transport level packetmarking in the uplink and downlink, downlink packet buffering, downlinkdata notification triggering, and/or the like.

In an example, the UE 100 IP address management may include allocationand release of the UE 100 IP address and/or renewal of the allocated IPaddress. The UE 100 may set a requested PDU type during a PDU sessionestablishment procedure based on its IP stack capabilities and/orconfiguration. In an example, the SMF 160 may select PDU type of a PDUsession. In an example, if the SMF 160 receives a request with PDU typeset to IP, the SMF 160 may select PDU type IPv4 or IPv6 based on DNNconfiguration and/or operator policies. In an example, the SMF 160 mayprovide a cause value to the UE 100 to indicate whether the other IPversion is supported on the DNN. In an example, if the SMF 160 receivesa request for PDU type IPv4 or IPv6 and the requested IP version issupported by the DNN the SMF 160 may select the requested PDU type.

In an example embodiment, the 5GC elements and UE 100 may support thefollowing mechanisms: during a PDU session establishment procedure, theSMF 160 may send the IP address to the UE 100 via SM NAS signaling. TheIPv4 address allocation and/or IPv4 parameter configuration via DHCPv4may be employed once PDU session may be established. IPv6 prefixallocation may be supported via IPv6 stateless autoconfiguration, ifIPv6 is supported. In an example, 5GC network elements may support IPv6parameter configuration via stateless DHCPv6.

The 5GC may support the allocation of a static IPv4 address and/or astatic IPv6 prefix based on subscription information in a UDM 140 and/orbased on the configuration on a per-subscriber, per-DNN basis.

User plane function(s) (UPF 110) may handle the user plane path of PDUsessions. A UPF 110 that provides the interface to a data network maysupport functionality of a PDU session anchor.

In an example, a policy control function, PCF 135, may support unifiedpolicy framework to govern network behavior, provide policy rules tocontrol plane function(s) to enforce policy rules, implement a front endto access subscription information relevant for policy decisions in auser data repository (UDR), and/or the like.

A network exposure function, NEF 125, may provide means to securelyexpose the services and capabilities provided by the 3GPP networkfunctions, translate between information exchanged with the AF 145 andinformation exchanged with the internal network functions, receiveinformation from other network functions, and/or the like.

In an example, an network repository function, NRF 130 may supportservice discovery function that may receive NF discovery request from NFinstance, provide information about the discovered NF instances (bediscovered) to the NF instance, and maintain information about availableNF instances and their supported services, and/or the like.

In an example, an NSSF 120 may select a set of network slice instancesserving the UE 100, may determine allowed NSSAI. In an example, the NSSF120 may determine the AMF 155 set to be employed to serve the UE 100,and/or, based on configuration, determine a list of candidate AMF 155(s)155 by querying the NRF 130.

In an example, stored data in a UDR may include at least usersubscription data, including at least subscription identifiers, securitycredentials, access and mobility related subscription data, sessionrelated subscription data, policy data, and/or the like.

In an example, an AUSF 150 may support authentication server function(AUSF 150).

In an example, an application function, AF 145, may interact with the3GPP core network to provide services. In an example, based on operatordeployment, application functions may be trusted by the operator tointeract directly with relevant network functions. Application functionsnot allowed by the operator to access directly the network functions mayuse an external exposure framework (e.g., via the NEF 125) to interactwith relevant network functions.

In an example, control plane interface between the (R)AN 105 and the 5Gcore may support connection of multiple different kinds of AN(s) (e.g.3GPP RAN 105, N3IWF 170 for Un-trusted access 165) to the 5GC via acontrol plane protocol. In an example, an N2 AP protocol may be employedfor both the 3GPP access 105 and non-3GPP access 165. In an example,control plane interface between the (R)AN 105 and the 5G core maysupport decoupling between AMF 155 and other functions such as SMF 160that may need to control the services supported by AN(s) (e.g. controlof the UP resources in the AN 105 for a PDU session).

In an example, the 5GC may provide policy information from the PCF 135to the UE 100. In an example, the policy information may comprise:access network discovery and selection policy, UE 100 route selectionpolicy (URSP), SSC mode selection policy (SSCMSP), network sliceselection policy (NSSP), DNN selection policy, non-seamless offloadpolicy, and/or the like.

In an example, as depicted in example FIG. 5A and FIG. 5B, theregistration management, RM may be employed to register or de-register aUE/user 100 with the network, and establish the user context in thenetwork. Connection management may be employed to establish and releasethe signaling connection between the UE 100 and the AMF 155.

In an example, a UE 100 may register with the network to receiveservices that require registration. In an example, the UE 100 may updateits registration with the network periodically in order to remainreachable (periodic registration update), or upon mobility (e.g.,mobility registration update), or to update its capabilities or tore-negotiate protocol parameters.

In an example, an initial registration procedure as depicted in exampleFIG. 8 and FIG. 9 may involve execution of network access controlfunctions (e.g. user authentication and access authorization based onsubscription profiles in UDM 140). Example FIG. 9 is a continuation ofthe initial registration procedure depicted in FIG. 8. As a result ofthe initial registration procedure, the identity of the serving AMF 155may be registered in a UDM 140.

In an example, the registration management, RM procedures may beapplicable over both 3GPP access 105 and non 3GPP access 165.

An example FIG. 5A may depict the RM states of a UE 100 as observed bythe UE 100 and AMF 155. In an example embodiment, two RM states may beemployed in the UE 100 and the AMF 155 that may reflect the registrationstatus of the UE 100 in the selected PLMN: RM-DEREGISTERED 500, andRM-REGISTERED 510. In an example, in the RM DEREGISTERED state 500, theUE 100 may not be registered with the network. The UE 100 context in theAMF 155 may not hold valid location or routing information for the UE100 so the UE 100 may not be reachable by the AMF 155. In an example,the UE 100 context may be stored in the UE 100 and the AMF 155. In anexample, in the RM REGISTERED state 510, the UE 100 may be registeredwith the network. In the RM-REGISTERED 510 state, the UE 100 may receiveservices that may require registration with the network.

In an example embodiment, two RM states may be employed in AMF 155 forthe UE 100 that may reflect the registration status of the UE 100 in theselected PLMN: RM-DEREGISTERED 520, and RM-REGISTERED 530.

As depicted in example FIG. 6A and FIG. 6B, connection management, CM,may comprise establishing and releasing a signaling connection between aUE 100 and an AMF 155 over N1 interface. The signaling connection may beemployed to enable NAS signaling exchange between the UE 100 and thecore network. The signaling connection between the UE 100 and the AMF155 may comprise both the AN signaling connection between the UE 100 andthe (R)AN 105 (e.g. RRC connection over 3GPP access) and the N2connection for the UE 100 between the AN and the AMF 155.

As depicted in example FIG. 6A and FIG. 6B, two CM states may beemployed for the NAS signaling connectivity of the UE 100 with the AMF155, CM-IDLE 600, 620 and CM-CONNECTED 610, 630. A UE 100 in CM-IDLE 600state may be in RM-REGISTERED 510 state and may have no NAS signalingconnection established with the AMF 155 over N1. The UE 100 may performcell selection, cell reselection, PLMN selection, and/or the like. A UE100 in CM-CONNECTED 610 state may have a NAS signaling connection withthe AMF 155 over N1.

In an example embodiment two CM states may be employed for the UE 100 atthe AMF 155, CM-IDLE 620 and CM-CONNECTED 630.

In an example, an RRC inactive state may apply to NG-RAN (e.g. it mayapply to NR and E-UTRA connected to 5G CN). The AMF 155, based onnetwork configuration, may provide assistance information to the NG RAN105, to assist the NG RAN's 105 decision whether the UE 100 may be sentto RRC inactive state. When a UE 100 is CM-CONNECTED 610 with RRCinactive state, the UE 100 may resume the RRC connection due to uplinkdata pending, mobile initiated signaling procedure, as a response to RAN105 paging, to notify the network that it has left the RAN 105notification area, and/or the like.

In an example, a NAS signaling connection management may includeestablishing and releasing a NAS signaling connection. A NAS signalingconnection establishment function may be provided by the UE 100 and theAMF 155 to establish the NAS signaling connection for the UE 100 inCM-IDLE 600 state. The procedure of releasing the NAS signalingconnection may be initiated by the 5G (R)AN 105 node or the AMF 155.

In an example, reachability management of a UE 100 may detect whetherthe UE 100 is reachable and may provide the UE 100 location (e.g. accessnode) to the network to reach the UE 100. Reachability management may bedone by paging the UE 100 and the UE 100 location tracking. The UE 100location tracking may include both UE 100 registration area tracking andUE 100 reachability tracking. The UE 100 and the AMF 155 may negotiateUE 100 reachability characteristics in CM-IDLE 600, 620 state duringregistration and registration update procedures.

In an example, two UE 100 reachability categories may be negotiatedbetween a UE 100 and an AMF 155 for CM-IDLE 600, 620 state. 1) UE 100reachability allowing mobile device terminated data while the UE 100 isCM-IDLE 600 mode. 2) Mobile initiated connection only (MICO) mode. The5GC may support a PDU connectivity service that provides exchange ofPDUs between the UE 100 and a data network identified by a DNN. The PDUconnectivity service may be supported via PDU sessions that areestablished upon request from the UE 100.

In an example, a PDU session may support one or more PDU session types.PDU sessions may be established (e.g. upon UE 100 request), modified(e.g. upon UE 100 and 5GC request) and/or released (e.g. upon UE 100 and5GC request) using NAS SM signaling exchanged over N1 between the UE 100and the SMF 160. Upon request from an application server, the 5GC may beable to trigger a specific application in the UE 100. When receiving thetrigger, the UE 100 may send it to the identified application in the UE100. The identified application in the UE 100 may establish a PDUsession to a specific DNN.

In an example, the 5G QoS model may support a QoS flow based frameworkas depicted in example FIG. 7. The 5G QoS model may support both QoSflows that require a guaranteed flow bit rate and QoS flows that may notrequire a guaranteed flow bit rate. In an example, the 5G QoS model maysupport reflective QoS. The QoS model may comprise flow mapping orpacket marking at the UPF 110 (CN_UP) 110, AN 105 and/or the UE 100. Inan example, packets may arrive from and/or destined to theapplication/service layer 730 of UE 100, UPF 110 (CN_UP) 110, and/or theAF 145.

In an example, the QoS flow may be a granularity of QoS differentiationin a PDU session. A QoS flow ID, QFI, may be employed to identify theQoS flow in the 5G system. In an example, user plane traffic with thesame QFI within a PDU session may receive the same traffic forwardingtreatment. The QFI may be carried in an encapsulation header on N3and/or N9 (e.g. without any changes to the end-to-end packet header). Inan example, the QFI may be applied to PDUs with different types ofpayload. The QFI may be unique within a PDU session.

In an example, the QoS parameters of a QoS flow may be provided to the(R)AN 105 as a QoS profile over N2 at PDU session establishment, QoSflow establishment, or when NG-RAN is used at every time the user planeis activated. In an example, a default QoS rule may be required forevery PDU session. The SMF 160 may allocate the QFI for a QoS flow andmay derive QoS parameters from the information provided by the PCF 135.In an example, the SMF 160 may provide the QFI together with the QoSprofile containing the QoS parameters of a QoS flow to the (R)AN 105.

In an example, 5G QoS flow may be a granularity for QoS forwardingtreatment in the 5G system. Traffic mapped to the same 5G QoS flow mayreceive the same forwarding treatment (e.g. scheduling policy, queuemanagement policy, rate shaping policy, RLC configuration, and/or thelike). In an example, providing different QoS forwarding treatment mayrequire separate 5G QoS flows.

In an example, a 5G QoS indicator may be a scalar that may be employedas a reference to a specific QoS forwarding behavior (e.g. packet lossrate, packet delay budget) to be provided to a 5G QoS flow. In anexample, the 5G QoS indicator may be implemented in the access networkby the 5QI referencing node specific parameters that may control the QoSforwarding treatment (e.g. scheduling weights, admission thresholds,queue management thresholds, link layer protocol configuration, and/orthe like.).

In an example, 5GC may support edge computing and may enable operator(s)and 3rd party services to be hosted close to the UE's access point ofattachment. The 5G core network may select a UPF 110 close to the UE 100and may execute the traffic steering from the UPF 110 to the local datanetwork via a N6 interface. In an example, the selection and trafficsteering may be based on the UE's 100 subscription data, UE 100location, the information from application function AF 145, policy,other related traffic rules, and/or the like. In an example, the 5G corenetwork may expose network information and capabilities to an edgecomputing application function. The functionality support for edgecomputing may include local routing where the 5G core network may selecta UPF 110 to route the user traffic to the local data network, trafficsteering where the 5G core network may select the traffic to be routedto the applications in the local data network, session and servicecontinuity to enable UE 100 and application mobility, user planeselection and reselection, e.g. based on input from applicationfunction, network capability exposure where 5G core network andapplication function may provide information to each other via NEF 125,QoS and charging where PCF 135 may provide rules for QoS control andcharging for the traffic routed to the local data network, support oflocal area data network where 5G core network may provide support toconnect to the LADN in a certain area where the applications aredeployed, and/or the like.

An example 5G system may be a 3GPP system comprising of 5G accessnetwork 105, 5G core network and a UE 100, and/or the like. AllowedNSSAI may be an NSSAI provided by a serving PLMN during e.g. aregistration procedure, indicating the NSSAI allowed by the network forthe UE 100 in the serving PLMN for the current registration area.

In an example, a PDU connectivity service may provide exchange of PDUsbetween a UE 100 and a data network. A PDU session may be an associationbetween the UE 100 and the data network, DN 115, that may provide thePDU connectivity service. The type of association may be IP, Ethernetand/or unstructured.

Establishment of user plane connectivity to a data network via networkslice instance(s) may comprise the following: performing a RM procedureto select an AMF 155 that supports the required network slices, andestablishing one or more PDU session(s) to the required data network viathe network slice instance(s).

In an example, the set of network slices for a UE 100 may be changed atany time while the UE 100 may be registered with the network, and may beinitiated by the network, or the UE 100.

In an example, a periodic registration update may be UE 100re-registration at expiry of a periodic registration timer. A requestedNSSAI may be a NSSAI that the UE 100 may provide to the network.

In an example, a service based interface may represent how a set ofservices may be provided/exposed by a given NF.

In an example, a service continuity may be an uninterrupted userexperience of a service, including the cases where the IP address and/oranchoring point may change. In an example, a session continuity mayrefer to continuity of a PDU session. For PDU session of IP type sessioncontinuity may imply that the IP address is preserved for the lifetimeof the PDU session. An uplink classifier may be a UPF 110 functionalitythat aims at diverting uplink traffic, based on filter rules provided bythe SMF 160, towards data network, DN 115.

In an example, the 5G system architecture may support data connectivityand services enabling deployments to use techniques such as e.g. networkfunction virtualization and/or software defined networking. The 5Gsystem architecture may leverage service-based interactions betweencontrol plane (CP) network functions where identified. In 5G systemarchitecture, separation of the user plane (UP) functions from thecontrol plane functions may be considered. A 5G system may enable anetwork function to interact with other NF(s) directly if required.

In an example, the 5G system may reduce dependencies between the accessnetwork (AN) and the core network (CN). The architecture may comprise aconverged access-agnostic core network with a common AN-CN interfacewhich may integrate different 3GPP and non-3GPP access types.

In an example, the 5G system may support a unified authenticationframework, stateless NFs, where the compute resource is decoupled fromthe storage resource, capability exposure, and concurrent access tolocal and centralized services. To support low latency services andaccess to local data networks, UP functions may be deployed close to theaccess network.

In an example, the 5G system may support roaming with home routedtraffic and/or local breakout traffic in the visited PLMN. An example 5Garchitecture may be service-based and the interaction between networkfunctions may be represented in two ways. (1) As service-basedrepresentation (depicted in example FIG. 1), where network functionswithin the control plane, may enable other authorized network functionsto access their services. This representation may also includepoint-to-point reference points where necessary. (2) Reference pointrepresentation, showing the interaction between the NF services in thenetwork functions described by point-to-point reference point (e.g. N11)between any two network functions.

In an example, a network slice may comprise the core network controlplane and user plane network functions, the 5G Radio Access Network; theN3IWF functions to the non-3GPP Access Network, and/or the like. Networkslices may differ for supported features and network functionimplementation. The operator may deploy multiple network slice instancesdelivering the same features but for different groups of UEs, e.g. asthey deliver a different committed service and/or because they may bededicated to a customer. The NSSF 120 may store the mapping informationbetween slice instance ID and NF ID (or NF address).

In an example, a UE 100 may simultaneously be served by one or morenetwork slice instances via a 5G-AN. In an example, the UE 100 may beserved by k network slices (e.g. k=8, 16, etc.) at a time. An AMF 155instance serving the UE 100 logically may belong to a network sliceinstance serving the UE 100.

In an example, a PDU session may belong to one specific network sliceinstance per PLMN. In an example, different network slice instances maynot share a PDU session. Different slices may have slice-specific PDUsessions using the same DNN.

An S-NSSAI (Single Network Slice Selection Assistance information) mayidentify a network slice. An S-NSSAI may comprise a slice/service type(SST), which may refer to the expected network slice behavior in termsof features and services; and/or a slice differentiator (SD). A slicedifferentiator may be optional information that may complement theslice/service type(s) to allow further differentiation for selecting anetwork slice instance from potentially multiple network slice instancesthat comply with the indicated slice/service type. In an example, thesame network slice instance may be selected employing differentS-NSSAIs. The CN part of a network slice instance(s) serving a UE 100may be selected by CN.

In an example, subscription data may include the S-NSSAI(s) of thenetwork slices that the UE 100 subscribes to. One or more S-NSSAIs maybe marked as default S-NSSAI. In an example, k S-NSSAI may be markeddefault S-NSSAI (e.g. k=8, 16, etc.). In an example, the UE 100 maysubscribe to more than 8 S-NSSAIs.

In an example, a UE 100 may be configured by the HPLMN with a configuredNSSAI per PLMN. Upon successful completion of a UE's registrationprocedure, the UE 100 may obtain from the AMF 155 an Allowed NSSAI forthis PLMN, which may include one or more S-NSSAIs.

In an example, the Allowed NSSAI may take precedence over the configuredNSSAI for a PLMN. The UE 100 may use the S-NSSAIs in the allowed NSSAIcorresponding to a network slice for the subsequent network sliceselection related procedures in the serving PLMN.

In an example, the establishment of user plane connectivity to a datanetwork via a network slice instance(s) may comprise: performing a RMprocedure to select an AMF 155 that may support the required networkslices, establishing one or more PDU sessions to the required datanetwork via the network slice instance(s), and/or the like.

In an example, when a UE 100 registers with a PLMN, if the UE 100 forthe PLMN has a configured NSSAI or an allowed NSSAI, the UE 100 mayprovide to the network in RRC and NAS layer a requested NSSAI comprisingthe S-NSSAI(s) corresponding to the slice(s) to which the UE 100attempts to register, a temporary user ID if one was assigned to the UE,and/or the like. The requested NSSAI may be configured-NSSAI,allowed-NSSAI, and/or the like.

In an example, when a UE 100 registers with a PLMN, if for the PLMN theUE 100 has no configured NSSAI or allowed NSSAI, the RAN 105 may routeNAS signaling from/to the UE 100 to/from a default AMF 155.

In an example, the network, based on local policies, subscriptionchanges and/or UE 100 mobility, may change the set of permitted networkslice(s) to which the UE 100 is registered. In an example, the networkmay perform the change during a registration procedure or trigger anotification towards the UE 100 of the change of the supported networkslices using an RM procedure (which may trigger a registrationprocedure). The network may provide the UE 100 with a new allowed NSSAIand tracking area list.

In an example, during a registration procedure in a PLMN, in case thenetwork decides that the UE 100 should be served by a different AMF 155based on network slice(s) aspects, the AMF 155 that first received theregistration request may redirect the registration request to anotherAMF 155 via the RAN 105 or via direct signaling between the initial AMF155 and the target AMF 155.

In an example, the network operator may provision the UE 100 withnetwork slice selection policy (NSSP). The NSSP may comprise one or moreNSSP rules.

In an example, if a UE 100 has one or more PDU sessions establishedcorresponding to a specific S-NSSAI, the UE 100 may route the user dataof the application in one of the PDU sessions, unless other conditionsin the UE 100 may prohibit the use of the PDU sessions. If theapplication provides a DNN, then the UE 100 may consider the DNN todetermine which PDU session to use. In an example, if the UE 100 doesnot have a PDU session established with the specific S-NSSAI, the UE 100may request a new PDU session corresponding to the S-NSSAI and with theDNN that may be provided by the application. In an example, in order forthe RAN 105 to select a proper resource for supporting network slicingin the RAN 105, the RAN 105 may be aware of the network slices used bythe UE 100.

In an example, an AMF 155 may select an SMF 160 in a network sliceinstance based on S-NSSAI, DNN and/or other information e.g. UE 100subscription and local operator policies, and/or the like, when the UE100 triggers the establishment of a PDU session. The selected SMF 160may establish the PDU session based on S-NSSAI and DNN.

In an example, in order to support network-controlled privacy of sliceinformation for the slices the UE 100 may access, when the UE 100 isaware or configured that privacy considerations may apply to NSSAI, theUE 100 may not include NSSAI in NAS signaling unless the UE 100 has aNAS security context and the UE 100 may not include NSSAI in unprotectedRRC signaling.

In an example, for roaming scenarios, the network slice specific networkfunctions in VPLMN and HPLMN may be selected based on the S-NSSAIprovided by the UE 100 during PDU connection establishment. If astandardized S-NSSAI is used, selection of slice specific NF instancesmay be done by each PLMN based on the provided S-NSSAI. In an example,the VPLMN may map the S-NSSAI of HPLMN to a S-NSSAI of VPLMN based onroaming agreement (e.g., including mapping to a default S-NSSAI ofVPLMN). In an example, the selection of slice specific NF instance inVPLMN may be done based on the S-NSSAI of VPLMN. In an example, theselection of any slice specific NF instance in HPLMN may be based on theS-NSSAI of HPLMN.

As depicted in example FIG. 8 and FIG. 9, a registration procedure maybe performed by the UE 100 to get authorized to receive services, toenable mobility tracking, to enable reachability, and/or the like.

In an example, the UE 100 may send to the (R)AN 105 an AN message(comprising AN parameters, RM-NAS registration request (registrationtype, SUCI or SUPI or 5G-GUTI, last visited TAI (if available), securityparameters, requested NSSAI, mapping of requested NSSAI, UE 100 5GCcapability, PDU session status, PDU session(s) to be re-activated,Follow on request, MICO mode preference, and/or the like), and/or thelike). In an example, in case of NG-RAN, the AN parameters may includee.g. SUCI or SUPI or the 5G-GUTI, the Selected PLMN ID and requestedNSSAI, and/or the like. In an example, the AN parameters may compriseestablishment cause. The establishment cause may provide the reason forrequesting the establishment of an RRC connection. In an example, theregistration type may indicate if the UE 100 wants to perform an initialregistration (i.e. the UE 100 is in RM-DEREGISTERED state), a mobilityregistration update (e.g., the UE 100 is in RM-REGISTERED state andinitiates a registration procedure due to mobility), a periodicregistration update (e.g., the UE 100 is in RM-REGISTERED state and mayinitiate a registration procedure due to the periodic registrationupdate timer expiry) or an emergency registration (e.g., the UE 100 isin limited service state). In an example, if the UE 100 performing aninitial registration (i.e., the UE 100 is in RM-DEREGISTERED state) to aPLMN for which the UE 100 does not already have a 5G-GUTI, the UE 100may include its SUCI or SUPI in the registration request. The SUCI maybe included if the home network has provisioned the public key toprotect SUPI in the UE. If the UE 100 received a UE 100 configurationupdate command indicating that the UE 100 needs to re-register and the5G-GUTI is invalid, the UE 100 may perform an initial registration andmay include the SUPI in the registration request message. For anemergency registration, the SUPI may be included if the UE 100 does nothave a valid 5G-GUTI available; the PEI may be included when the UE 100has no SUPI and no valid 5G-GUTI. In other cases, the 5G-GUTI may beincluded and it may indicate the last serving AMF 155. If the UE 100 isalready registered via a non-3GPP access in a PLMN different from thenew PLMN (e.g., not the registered PLMN or an equivalent PLMN of theregistered PLMN) of the 3GPP access, the UE 100 may not provide over the3GPP access the 5G-GUTI allocated by the AMF 155 during the registrationprocedure over the non-3GPP access. If the UE 100 is already registeredvia a 3GPP access in a PLMN (e.g., the registered PLMN), different fromthe new PLMN (i.e. not the registered PLMN or an equivalent PLMN of theregistered PLMN) of the non-3GPP access, the UE 100 may not provide overthe non-3GPP access the 5G-GUTI allocated by the AMF 155 during theregistration procedure over the 3GPP access. The UE 100 may provide theUE's usage setting based on its configuration. In case of initialregistration or mobility registration update, the UE 100 may include themapping of requested NSSAI, which may be the mapping of each S-NSSAI ofthe requested NSSAI to the S-NSSAIs of the configured NSSAI for theHPLMN, to ensure that the network is able to verify whether theS-NSSAI(s) in the requested NSSAI are permitted based on the subscribedS-NSSAIs. If available, the last visited TAI may be included in order tohelp the AMF 155 produce registration area for the UE. In an example,the security parameters may be used for authentication and integrityprotection. requested NSSAI may indicate the network slice selectionassistance information. The PDU session status may indicates thepreviously established PDU sessions in the UE. When the UE 100 isconnected to the two AMF 155 belonging to different PLMN via 3GPP accessand non-3GPP access then the PDU session status may indicate theestablished PDU session of the current PLMN in the UE. The PDUsession(s) to be re-activated may be included to indicate the PDUsession(s) for which the UE 100 may intend to activate UP connections. APDU session corresponding to a LADN may not be included in the PDUsession(s) to be re-activated when the UE 100 is outside the area ofavailability of the LADN. The follow on request may be included when theUE 100 may have pending uplink signaling and the UE 100 may not includePDU session(s) to be re-activated, or the registration type may indicatethe UE 100 may want to perform an emergency registration.

In an example, if a SUPI is included or the 5G-GUTI does not indicate avalid AMF 155, the (R)AN 105, based on (R)AT and requested NSSAI, ifavailable, may selects

an AMF 155. If UE 100 is in CM-CONNECTED state, the (R)AN 105 mayforward the registration request message to the AMF 155 based on the N2connection of the UE. If the (R)AN 105 may not select an appropriate AMF155, it may forward the registration request to an AMF 155 which hasbeen configured, in (R)AN 105, to perform AMF 155 selection.

In an example, the (R)AN 105 may send to the new AMF 155 an N2 message(comprising: N2 parameters, RM-NAS registration request (registrationtype, SUPI or 5G-GUTI, last visited TAI (if available), securityparameters, requested NSSAI, mapping of requested NSSAI, UE 100 5GCcapability, PDU session status, PDU session(s) to be re-activated,follow on request, and MICO mode preference), and/or the like). In anexample, when NG-RAN is used, the N2 parameters may comprise theselected PLMN ID, location information, cell identity and the RAT typerelated to the cell in which the UE 100 is camping. In an example, whenNG-RAN is used, the N2 parameters may include the establishment cause.

In an example, the new AMF 155 may send to the old AMF 155 anNamf_Communication_UEContextTransfer (complete registration request). Inan example, if the UE's 5G-GUTI was included in the registration requestand the serving AMF 155 has changed since last registration procedure,the new AMF 155 may invoke the Namf_Communication_UEContextTransferservice operation on the old AMF 155 including the complete registrationrequest IE, which may be integrity protected, to request the UE's SUPIand MM Context. The old AMF 155 may use the integrity protected completeregistration request IE to verify if the context transfer serviceoperation invocation corresponds to the UE 100 requested. In an example,the old AMF 155 may transfer the event subscriptions information by eachNF consumer, for the UE, to the new AMF 155. In an example, if the UE100 identifies itself with PEI, the SUPI request may be skipped.

In an example, the old AMF 155 may send to new AMF 155 a response toNamf_Communication_UEContextTransfer (SUPI, MM context, SMF 160information, PCF ID). In an example, the old AMF 155 may respond to thenew AMF 155 for the Namf_Communication_UEContextTransfer invocation byincluding the UE's SUPI and MM context. In an example, if old AMF 155holds information about established PDU sessions, the old AMF 155 mayinclude SMF 160 information including S-NSSAI(s), SMF 160 identities andPDU session ID. In an example, if old AMF 155 holds information aboutactive NGAP UE-TNLA bindings to N3IWF, the old AMF 155 may includeinformation about the NGAP UE-TNLA bindings.

In an example, if the SUPI is not provided by the UE 100 nor retrievedfrom the old AMF 155 the identity request procedure may be initiated bythe AMF 155 sending an identity request message to the UE 100 requestingthe SUCI.

In an example, the UE 100 may respond with an identity response messageincluding the SUCI. The UE 100 may derive the SUCI by using theprovisioned public key of the HPLMN.

In an example, the AMF 155 may decide to initiate UE 100 authenticationby invoking an AUSF 150. The AMF 155 may select an AUSF 150 based onSUPI or SUCI. In an example, if the AMF 155 is configured to supportemergency registration for unauthenticated SUPIs and the UE 100indicated registration type emergency registration the AMF 155 may skipthe authentication and security setup or the AMF 155 may accept that theauthentication may fail and may continue the registration procedure.

In an example, the authentication may be performed byNudm_UEAuthenticate_Get operation. The AUSF 150 may discover a UDM 140.In case the AMF 155 provided a SUCI to AUSF 150, the AUSF 150 may returnthe SUPI to AMF 155 after the authentication is successful. In anexample, if network slicing is used, the AMF 155 may decide if theregistration request needs to be rerouted where the initial AMF 155refers to the AMF 155. In an example, the AMF 155 may initiate NASsecurity functions. In an example, upon completion of NAS securityfunction setup, the AMF 155 may initiate NGAP procedure to enable 5G-ANuse it for securing procedures with the UE. In an example, the 5G-AN maystore the security context and may acknowledge to the AMF 155. The 5G-ANmay use the security context to protect the messages exchanged with theUE.

In an example, new AMF 155 may send to the old AMF 155Namf_Communication_RegistrationCompleteNotify. If the AMF 155 haschanged, the new AMF 155 may notify the old AMF 155 that theregistration of the UE 100 in the new AMF 155 may be completed byinvoking the Namf_Communication_RegistrationCompleteNotify serviceoperation. If the authentication/security procedure fails, then theregistration may be rejected, and the new AMF 155 may invoke theNamf_Communication_RegistrationCompleteNotify service operation with areject indication reason code towards the old AMF 155. The old AMF 155may continue as if the UE 100 context transfer service operation wasnever received. If one or more of the S-NSSAIs used in the oldregistration area may not be served in the target registration area, thenew AMF 155 may determine which PDU session may not be supported in thenew registration area. The new AMF 155 may invoke theNamf_Communication_RegistrationCompleteNotify service operationincluding the rejected PDU session ID and a reject cause (e.g. theS-NSSAI becomes no longer available) towards the old AMF 155. The newAMF 155 may modify the PDU session status correspondingly. The old AMF155 may inform the corresponding SMF 160(s) to locally release the UE'sSM context by invoking the Nsmf_PDUSession_ReleaseSMContext serviceoperation.

In an example, the new AMF 155 may send to the UE 100 an identityrequest/response (e.g., PEI). If the PEI was not provided by the UE 100nor retrieved from the old AMF 155, the identity request procedure maybe initiated by AMF 155 sending an identity request message to the UE100 to retrieve the PEI. The PEI may be transferred encrypted unless theUE 100 performs emergency registration and may not be authenticated. Foran emergency registration, the UE 100 may have included the PEI in theregistration request.

In an example, the new AMF 155 may initiate ME identity check byinvoking the N5g-eir_EquipmentIdentityCheck_Get service operation.

In an example, the new AMF 155, based on the SUPI, may select a UDM 140.The UDM 140 may select a UDR instance. In an example, the AMF 155 mayselects a UDM 140.

In an example, if the AMF 155 has changed since the last registrationprocedure, or if the UE 100 provides a SUPI which may not refer to avalid context in the AMF 155, or if the UE 100 registers to the same AMF155 it has already registered to a non-3GPP access (e.g., the UE 100 isregistered over a non-3GPP access and may initiate the registrationprocedure to add a 3GPP access), the new AMF 155 may register with theUDM 140 using Nudm_UECM_Registration and may subscribe to be notifiedwhen the UDM 140 may deregister the AMF 155. The UDM 140 may store theAMF 155 identity associated to the access type and may not remove theAMF 155 identity associated to the other access type. The UDM 140 maystore information provided at registration in UDR, by Nudr_UDM_Update.In an example, the AMF 155 may retrieve the access and mobilitysubscription data and SMF 160 selection subscription data usingNudm_SDM_Get. The UDM 140 may retrieve this information from UDR byNudr_UDM_Query(access and mobility subscription data). After asuccessful response is received, the AMF 155 may subscribe to benotified using Nudm_SDM_Subscribe when the data requested may bemodified. The UDM 140 may subscribe to UDR by Nudr_UDM_Subscribe. TheGPSI may be provided to the AMF 155 in the subscription data from theUDM 140 if the GPSI is available in the UE 100 subscription data. In anexample, the new AMF 155 may provide the access type it serves for theUE 100 to the UDM 140 and the access type may be set to 3GPP access. TheUDM 140 may store the associated access type together with the servingAMF 155 in UDR by Nudr_UDM_Update. The new AMF 155 may create an MMcontext for the UE 100 after getting the mobility subscription data fromthe UDM 140. In an example, when the UDM 140 stores the associatedaccess type together with the serving AMF 155, the UDM 140 may initiatea Nudm_UECM_DeregistrationNotification to the old AMF 155 correspondingto 3GPP access. The old AMF 155 may remove the MM context of the UE. Ifthe serving NF removal reason indicated by the UDM 140 is initialregistration, then the old AMF 155 may invoke theNamf_EventExposure_Notify service operation towards all the associatedSMF 160 s of the UE 100 to notify that the UE 100 is deregistered fromold AMF 155. The SMF 160 may release the PDU session(s) on getting thisnotification. In an example, the old AMF 155 may unsubscribe with theUDM 140 for subscription data using Nudm_SDM_unsubscribe.

In an example, if the AMF 155 decides to initiate PCF 135 communication,e.g. the AMF 155 has not yet obtained access and mobility policy for theUE 100 or if the access and mobility policy in the AMF 155 are no longervalid, the AMF 155 may select a PCF 135. If the new AMF 155 receives aPCF ID from the old AMF 155 and successfully contacts the PCF 135identified by the PCF ID, the AMF 155 may select the (V-)PCF identifiedby the PCF ID. If the PCF 135 identified by the PCF ID may not be used(e.g. no response from the PCF 135) or if there is no PCF ID receivedfrom the old AMF 155, the AMF 155 may select a PCF 135.

In an example, the new AMF 155 may perform a policy associationestablishment during registration procedure. If the new AMF 155 contactsthe PCF 135 identified by the (V-) PCF ID received during inter-AMF 155mobility, the new AMF 155 may include the PCF-ID in theNpcf_AMPolicyControl Get operation. If the AMF 155 notifies the mobilityrestrictions (e.g. UE 100 location) to the PCF 135 for adjustment, or ifthe PCF 135 updates the mobility restrictions itself due to someconditions (e.g. application in use, time and date), the PCF 135 mayprovide the updated mobility restrictions to the AMF 155.

In an example, the PCF 135 may invoke Namf_EventExposure_Subscribeservice operation for UE 100 event subscription.

In an example, the AMF 155 may send to the SMF 160 anNsmf_PDUSession_UpdateSMContext. In an example, the AMF 155 may invokethe Nsmf_PDUSession_UpdateSMContext if the PDU session(s) to bere-activated is included in the registration request. The AMF 155 maysend Nsmf_PDUSession_UpdateSMContext request to SMF 160(s) associatedwith the PDU session(s) to activate user plane connections of the PDUsession(s). The SMF 160 may decide to trigger e.g. the intermediate UPF110 insertion, removal or change of PSA. In the case that theintermediate UPF 110 insertion, removal, or relocation is performed forthe PDU session(s) not included in PDU session(s) to be re-activated,the procedure may be performed without N11 and N2 interactions to updatethe N3 user plane between (R)AN 105 and 5GC. The AMF 155 may invoke theNsmf_PDUSession_ReleaseSMContext service operation towards the SMF 160if any PDU session status indicates that it is released at the UE 100.The AMF 155 may invoke the Nsmf_PDUSession_ReleaseSMContext serviceoperation towards the SMF 160 in order to release any network resourcesrelated to the PDU session.

In an example, the new AMF 155155 may send to a N3IWF an N2 AMF 155mobility request. If the AMF 155 has changed, the new AMF 155 may createan NGAP UE 100 association towards the N3IWF to which the UE 100 isconnected. In an example, the N3IWF may respond to the new AMF 155 withan N2 AMF 155 mobility response.

In an example, the new AMF 155 may send to the UE 100 a registrationaccept (comprising: 5G-GUTI, registration area, mobility restrictions,PDU session status, allowed NSSAI, [mapping of allowed NSSAI], periodicregistration update timer, LADN information and accepted MICO mode, IMSvoice over PS session supported indication, emergency service supportindicator, and/or the like). In an example, the AMF 155 may send theregistration accept message to the UE 100 indicating that theregistration request has been accepted. 5G-GUTI may be included if theAMF 155 allocates a new 5G-GUTI. If the AMF 155 allocates a newregistration area, it may send the registration area to the UE 100 viaregistration accept message. If there is no registration area includedin the registration accept message, the UE 100 may consider the oldregistration area as valid. In an example, mobility restrictions may beincluded in case mobility restrictions may apply for the UE 100 andregistration type may not be emergency registration. The AMF 155 mayindicate the established PDU sessions to the UE 100 in the PDU sessionstatus. The UE 100 may remove locally any internal resources related toPDU sessions that are not marked as established in the received PDUsession status. In an example, when the UE 100 is connected to the twoAMF 155 belonging to different PLMN via 3GPP access and non-3GPP accessthen the UE 100 may remove locally any internal resources related to thePDU session of the current PLMN that are not marked as established inreceived PDU session status. If the PDU session status information wasin the registration request, the AMF 155 may indicate the PDU sessionstatus to the UE. The mapping of allowed NSSAI may be the mapping ofeach S-NSSAI of the allowed NSSAI to the S-NSSAIs of the configuredNSSAI for the HPLMN. The AMF 155 may include in the registration acceptmessage the LADN information for LADNs that are available within theregistration area determined by the AMF 155 for the UE. If the UE 100included MICO mode in the request, then AMF 155 may respond whether MICOmode may be used. The AMF 155 may set the IMS voice over PS sessionsupported Indication. In an example, in order to set the IMS voice overPS session supported indication, the AMF 155 may perform a UE/RAN radioinformation and compatibility request procedure to check thecompatibility of the UE 100 and RAN radio capabilities related to IMSvoice over PS. In an example, the emergency service support indicatormay inform the UE 100 that emergency services are supported, e.g., theUE 100 may request PDU session for emergency services. In an example,the handover restriction list and UE-AMBR may be provided to NG-RAN bythe AMF 155.

In an example, the UE 100 may send to the new AMF 155 a registrationcomplete message. In an example, the UE 100 may send the registrationcomplete message to the AMF 155 to acknowledge that a new 5G-GUTI may beassigned. In an example, when information about the PDU session(s) to bere-activated is not included in the registration request, the AMF 155may release the signaling connection with the UE 100. In an example,when the follow-on request is included in the registration request, theAMF 155 may not release the signaling connection after the completion ofthe registration procedure. In an example, if the AMF 155 is aware thatsome signaling is pending in the AMF 155 or between the UE 100 and the5GC, the AMF 155 may not release the signaling connection after thecompletion of the registration procedure.

As depicted in example FIG. 10 and FIG. 11, a service request proceduree.g., a UE 100 triggered service request procedure may be used by a UE100 in CM-IDLE state to request the establishment of a secure connectionto an AMF 155. FIG. 11 is continuation of FIG. 10 depicting the servicerequest procedure. The service request procedure may be used to activatea user plane connection for an established PDU session. The servicerequest procedure may be triggered by the UE 100 or the 5GC, and may beused when the UE 100 is in CM-IDLE and/or in CM-CONNECTED and may allowselectively to activate user plane connections for some of theestablished PDU sessions.

In an example, a UE 100 in CM IDLE state may initiate the servicerequest procedure to send uplink signaling messages, user data, and/orthe like, as a response to a network paging request, and/or the like. Inan example, after receiving the service request message, the AMF 155 mayperform authentication. In an example, after the establishment ofsignaling connection to the AMF 155, the UE 100 or network may sendsignaling messages, e.g. PDU session establishment from the UE 100 to aSMF 160, via the AMF 155.

In an example, for any service request, the AMF 155 may respond with aservice accept message to synchronize PDU session status between the UE100 and network. The AMF 155 may respond with a service reject messageto the UE 100, if the service request may not be accepted by thenetwork. The service reject message may include an indication or causecode requesting the UE 100 to perform a registration update procedure.In an example, for service request due to user data, network may takefurther actions if user plane connection activation may not besuccessful. In an example FIG. 10 and FIG. 11, more than one UPF, e.g.,old UPF 110-2 and PDU session Anchor PSA UPF 110-3 may be involved.

In an example, the UE 100 may send to a (R)AN 105 an AN messagecomprising AN parameters, mobility management, MM NAS service request1005 (e.g., list of PDU sessions to be activated, list of allowed PDUsessions, security parameters, PDU session status, and/or the like),and/or the like. In an example, the UE 100 may provide the list of PDUsessions to be activated when the UE 100 may re-activate the PDUsession(s). The list of allowed PDU sessions may be provided by the UE100 when the service request may be a response of a paging or a NASnotification, and may identify the PDU sessions that may be transferredor associated to the access on which the service request may be sent. Inan example, for the case of NG-RAN, the AN parameters may includeselected PLMN ID, and an establishment cause. The establishment causemay provide the reason for requesting the establishment of an RRCconnection. The UE 100 may send NAS service request message towards theAMF 155 encapsulated in an RRC message to the RAN 105.

In an example, if the service request may be triggered for user data,the UE 100 may identify, using the list of PDU sessions to be activated,the PDU session(s) for which the UP connections are to be activated inthe NAS service request message. If the service request may be triggeredfor signaling, the UE 100 may not identify any PDU session(s). If thisprocedure may be triggered for paging response, and/or the UE 100 mayhave at the same time user data to be transferred, the UE 100 mayidentify the PDU session(s) whose UP connections may be activated in MMNAS service request message, by the list of PDU sessions to beactivated.

In an example, if the service request over 3GPP access may be triggeredin response to a paging indicating non-3GPP access, the NAS servicerequest message may identify in the list of allowed PDU sessions thelist of PDU sessions associated with the non-3GPP access that may bere-activated over 3GPP. In an example, the PDU session status mayindicate the PDU sessions available in the UE 100. In an example, the UE100 may not trigger the service request procedure for a PDU sessioncorresponding to a LADN when the UE 100 may be outside the area ofavailability of the LADN. The UE 100 may not identify such PDUsession(s) in the list of PDU sessions to be activated, if the servicerequest may be triggered for other reasons.

In an example, the (R)AN 105 may send to AMF 155 an N2 Message 1010(e.g., a service request) comprising N2 parameters, MM NAS servicerequest, and/or the like. The AMF 155 may reject the N2 message if itmay not be able to handle the service request. In an example, if NG-RANmay be used, the N2 parameters may include the 5G-GUTI, selected PLMNID, location information, RAT type, establishment cause, and/or thelike. In an example, the 5G-GUTI may be obtained in RRC procedure andthe (R)AN 105 may select the AMF 155 according to the 5G-GUTI. In anexample, the location information and RAT type may relate to the cell inwhich the UE 100 may be camping. In an example, based on the PDU sessionstatus, the AMF 155 may initiate PDU session release procedure in thenetwork for the PDU sessions whose PDU session ID(s) may be indicated bythe UE 100 as not available.

In an example, if the service request was not sent integrity protectedor integrity protection verification failed, the AMF 155 may initiate aNAS authentication/security procedure 1015.

In an example, if the UE 100 triggers the service request to establish asignaling connection, upon successful establishment of the signalingconnection, the UE 100 and the network may exchange NAS signaling.

In an example the AMF 155 may send to the SMF 160 a PDU session updatecontext request 1020 e.g., Nsmf_PDUSession_UpdateSMContext requestcomprising PDU session ID(s), Cause(s), UE 100 location information,access type, and/or the like.

In an example, the Nsmf_PDUSession_UpdateSMContext request may beinvoked by the AMF 155 if the UE 100 may identify PDU session(s) to beactivated in the NAS service request message. In an example, theNsmf_PDUSession_UpdateSMContext request may be triggered by the SMF 160wherein the PDU session(s) identified by the UE 100 may correlate toother PDU session ID(s) than the one triggering the procedure. In anexample, the Nsmf_PDUSession_UpdateSMContext request may be triggered bythe SMF 160 wherein the current UE 100 location may be outside the areaof validity for the N2 information provided by the SMF 160 during anetwork triggered service request procedure. The AMF 155 may not sendthe N2 information provided by the SMF 160 during the network triggeredservice request procedure.

In an example, the AMF 155 may determine the PDU session(s) to beactivated and may send an Nsmf_PDUSession_UpdateSMContext request to SMF160(s) associated with the PDU session(s) with cause set to indicateestablishment of user plane resources for the PDU session(s).

In an example, if the procedure may be triggered in response to pagingindicating non-3GPP access, and the list of allowed PDU sessionsprovided by the UE 100 may not include the PDU session for which the UE100 was paged, the AMF 155 may notify the SMF 160 that the user planefor the PDU session may not be re-activated. The service requestprocedure may succeed without re-activating the user plane of any PDUsessions, and the AMF 155 may notify the UE 100.

In an example, if the PDU session ID may correspond to a LADN and theSMF 160 may determine that the UE 100 may be outside the area ofavailability of the LADN based on the UE 100 location reporting from theAMF 155, the SMF 160 may decide to (based on local policies) keep thePDU session, may reject the activation of user plane connection for thePDU session and may inform the AMF 155. In an example, if the proceduremay be triggered by a network triggered service request, the SMF 160 maynotify the UPF 110 that originated the data notification to discarddownlink data for the PDU sessions and/or to not provide further datanotification messages. The SMF 160 may respond to the AMF 155 with anappropriate reject cause and the user plane activation of PDU sessionmay be stopped.

In an example, if the PDU session ID may correspond to a LADN and theSMF 160 may determine that the UE 100 may be outside the area ofavailability of the LADN based on the UE 100 location reporting from theAMF 155, the SMF 160 may decide to (based on local policies) release thePDU session. The SMF 160 may locally release the PDU session and mayinform the AMF 155 that the PDU session may be released. The SMF 160 mayrespond to the AMF 155 with an appropriate reject cause and the userplane Activation of PDU session may be stopped.

In an example, if the UP activation of the PDU session may be acceptedby the SMF 160, based on the location info received from the AMF 155,the SMF 160 may check the UPF 110 Selection 1025 Criteria (e.g., sliceisolation requirements, slice coexistence requirements, UPF's 110dynamic load, UPF's 110 relative static capacity among UPFs supportingthe same DNN, UPF 110 location available at the SMF 160, UE 100 locationinformation, Capability of the UPF 110 and the functionality requiredfor the particular UE 100 session. In an example, an appropriate UPF 110may be selected by matching the functionality and features required fora UE 100, DNN, PDU session type (i.e. IPv4, IPv6, ethernet type orunstructured type) and if applicable, the static IP address/prefix, SSCmode selected for the PDU session, UE 100 subscription profile in UDM140, DNAI as included in the PCC rules, local operator policies,S-NSSAI, access technology being used by the UE 100, UPF 110 logicaltopology, and/or the like), and may determine to perform one or more ofthe following: continue using the current UPF(s); may select a newintermediate UPF 110 (or add/remove an intermediate UPF 110), if the UE100 has moved out of the service area of the UPF 110 that was previouslyconnecting to the (R)AN 105, while maintaining the UPF(s) acting as PDUsession anchor; may trigger re-establishment of the PDU session toperform relocation/reallocation of the UPF 110 acting as PDU sessionanchor, e.g. the UE 100 has moved out of the service area of the anchorUPF 110 which is connecting to RAN 105.

In an example, the SMF 160 may send to the UPF 110 (e.g., newintermediate UPF 110) an N4 session establishment request 1030. In anexample, if the SMF 160 may select a new UPF 110 to act as intermediateUPF 110-2 for the PDU session, or if the SMF 160 may select to insert anintermediate UPF 110 for a PDU session which may not have anintermediate UPF 110-2, an N4 session establishment request 1030 messagemay be sent to the new UPF 110, providing packet detection, dataforwarding, enforcement and reporting rules to be installed on the newintermediate UPF. The PDU session anchor addressing information (on N9)for this PDU session may be provided to the intermediate UPF 110-2.

In an example, if a new UPF 110 is selected by the SMF 160 to replacethe old (intermediate) UPF 110-2, the SMF 160 may include a dataforwarding indication. The data forwarding indication may indicate tothe UPF 110 that a second tunnel endpoint may be reserved for bufferedDL data from the old I-UPF.

In an example, the new UPF 110 (intermediate) may send to SMF 160 an N4session establishment response message 1030. In case the UPF 110 mayallocate CN tunnel info, the UPF 110 may provide DL CN tunnel info forthe UPF 110 acting as PDU session anchor and UL CN tunnel info (e.g., CNN3 tunnel info) to the SMF 160. If the data forwarding indication may bereceived, the new (intermediate) UPF 110 acting as N3 terminating pointmay send DL CN tunnel info for the old (intermediate) UPF 110-2 to theSMF 160. The SMF 160 may start a timer, to release the resource in theold intermediate UPF 110-2.

In an example, if the SMF 160 may selects a new intermediate UPF 110 forthe PDU session or may remove the old I-UPF 110-2, the SMF 160 may sendN4 session modification request message 1035 to PDU session anchor, PSAUPF 110-3, providing the data forwarding indication and DL tunnelinformation from new intermediate UPF 110.

In an example, if the new intermediate UPF 110 may be added for the PDUsession, the (PSA) UPF 110-3 may begin to send the DL data to the newI-UPF 110 as indicated in the DL tunnel information.

In an example, if the service request may be triggered by the network,and the SMF 160 may remove the old I-UPF 110-2 and may not replace theold I-UPF 110-2 with the new I-UPF 110, the SMF 160 may include the dataforwarding indication in the request. The data forwarding indication mayindicate to the (PSA) UPF 110-3 that a second tunnel endpoint may bereserved for buffered DL data from the old I-UPF 110-2. In this case,the PSA UPF 110-3 may begin to buffer the DL data it may receive at thesame time from the N6 interface.

In an example, the PSA UPF 110-3 (PSA) may send to the SMF 160 an N4session modification response 1035. In an example, if the dataforwarding indication may be received, the PSA UPF 110-3 may become asN3 terminating point and may send CN DL tunnel info for the old(intermediate) UPF 110-2 to the SMF 160. The SMF 160 may start a timer,to release the resource in old intermediate UPF 110-2 if there is one.

In an example, the SMF 160 may send to the old UPF 110-2 an N4 sessionmodification request 1045 (e.g., may comprise new UPF 110 address, newUPF 110 DL tunnel ID, and/or the like). In an example, if the servicerequest may be triggered by the network, and/or the SMF 160 may removethe old (intermediate) UPF 110-2, the SMF 160 may send the N4 sessionmodification request message to the old (intermediate) UPF 110-2, andmay provide the DL tunnel information for the buffered DL data. If theSMF 160 may allocate new I-UPF 110, the DL tunnel information is fromthe new (intermediate) UPF 110 may act as N3 terminating point. If theSMF 160 may not allocate a new I-UPF 110, the DL tunnel information maybe from the new UPF 110 (PSA) 110-3 acting as N3 terminating point. TheSMF 160 may start a timer to monitor the forwarding tunnel. In anexample, the old (intermediate) UPF 110-2 may send N4 sessionmodification response message to the SMF 160.

In an example, if the I-UPF 110-2 may be relocated and forwarding tunnelwas established to the new I-UPF 110, the old (intermediate) UPF 110-2may forward its buffered data to the new (intermediate) UPF 110 actingas N3 terminating point. In an example, if the old I-UPF 110-2 may beremoved and the new I-UPF 110 may not be assigned for the PDU sessionand forwarding tunnel may be established to the UPF 110 (PSA) 110-3, theold (intermediate) UPF 110-2 may forward its buffered data to the UPF110 (PSA) 110-3 acting as N3 terminating point.

In an example, the SMF 160 may send to the AMF 155 an N11 message 1060e.g., a Nsmf_PDUSession_UpdateSMContext response (comprising: N1 SMcontainer (PDU session ID, PDU session re-establishment indication), N2SM information (PDU session ID, QoS profile, CN N3 tunnel info,S-NSSAI), Cause), upon reception of the Nsmf_PDUSession_UpdateSMContextrequest with a cause including e.g., establishment of user planeresources. The SMF 160 may determine whether UPF 110 reallocation may beperformed, based on the UE 100 location information, UPF 110 servicearea and operator policies. In an example, for a PDU session that theSMF 160 may determine to be served by the current UPF 110, e.g., PDUsession anchor or intermediate UPF, the SMF 160 may generate N2 SMinformation and may send an Nsmf_PDUSession_UpdateSMContext response1060 to the AMF 155 to establish the user plane(s). The N2 SMinformation may contain information that the AMF 155 may provide to theRAN 105. In an example, for a PDU session that the SMF 160 may determineas requiring a UPF 110 relocation for PDU session anchor UPF, the SMF160 may reject the activation of UP of the PDU session by sendingNsmf_PDUSession_UpdateSMContext response that may contain N1 SMcontainer to the UE 100 via the AMF 155. The N1 SM container may includethe corresponding PDU session ID and PDU session re-establishmentindication.

Upon reception of the Namf_EventExposure_Notify from the AMF 155 to theSMF 160, with an indication that the UE 100 is reachable, if the SMF 160may have pending DL data, the SMF 160 may invoke theNamf_Communication_N1N2MessageTransfer service operation to the AMF 155to establish the user plane(s) for the PDU sessions. In an example, theSMF 160 may resume sending DL data notifications to the AMF 155 in caseof DL data.

In an example, the SMF 160 may send a message to the AMF 155 to rejectthe activation of UP of the PDU session by including a cause in theNsmf_PDUSession_UpdateSMContext response if the PDU session maycorrespond to a LADN and the UE 100 may be outside the area ofavailability of the LADN, or if the AMF 155 may notify the SMF 160 thatthe UE 100 may be reachable for regulatory prioritized service, and thePDU session to be activated may not for a regulatory prioritizedservice; or if the SMF 160 may decide to perform PSA UPF 110-3relocation for the requested PDU session.

In an example, the AMF 155 may send to the (R)AN 105 an N2 requestmessage 1065 (e.g., N2 SM information received from SMF 160, securitycontext, AMF 155 signaling connection ID, handover restriction list, MMNAS service accept, list of recommended cells/TAs/NG-RAN nodeidentifiers). In an example, the RAN 105 may store the security context,AMF 155 signaling connection Id, QoS information for the QoS flows ofthe PDU sessions that may be activated and N3 tunnel IDs in the UE 100RAN 105 context. In an example, the MM NAS service accept may includePDU session status in the AMF 155. If the activation of UP of a PDUsession may be rejected by the SMF 160, the MM NAS service accept mayinclude the PDU session ID and the reason why the user plane resourcesmay not be activated (e.g. LADN not available). Local PDU sessionrelease during the session request procedure may be indicated to the UE100 via the session Status.

In an example, if there are multiple PDU sessions that may involvemultiple SMF 160 s, the AMF 155 may not wait for responses from all SMF160 s before it may send N2 SM information to the UE 100. The AMF 155may wait for all responses from the SMF 160 s before it may send MM NASservice accept message to the UE 100.

In an example, the AMF 155 may include at least one N2 SM informationfrom the SMF 160 if the procedure may be triggered for PDU session userplane activation. AMF 155 may send additional N2 SM information from SMF160 s in separate N2 message(s) (e.g. N2 tunnel setup request), if thereis any. Alternatively, if multiple SMF 160 s may be involved, the AMF155 may send one N2 request message to (R)AN 105 after all theNsmf_PDUSession_UpdateSMContext response service operations from all theSMF 160 s associated with the UE 100 may be received. In such case, theN2 request message may include the N2 SM information received in each ofthe Nsmf_PDUSession_UpdateSMContext response and PDU session ID toenable AMF 155 to associate responses to relevant SMF 160.

In an example, if the RAN 105 (e.g., NG RAN) node may provide the listof recommended cells/TAs/NG-RAN node identifiers during the AN releaseprocedure, the AMF 155 may include the information from the list in theN2 request. The RAN 105 may use this information to allocate the RAN 105notification area when the RAN 105 may decide to enable RRC inactivestate for the UE 100.

If the AMF 155 may receive an indication, from the SMF 160 during a PDUsession establishment procedure that the UE 100 may be using a PDUsession related to latency sensitive services, for any of the PDUsessions established for the UE 100 and the AMF 155 has received anindication from the UE 100 that may support the CM-CONNECTED with RRCinactive state, then the AMF 155 may include the UE's RRC inactiveassistance information. In an example, the AMF 155 based on networkconfiguration, may include the UE's RRC inactive assistance information.

In an example, the (R)AN 105 may send to the UE 100 a message to performRRC connection reconfiguration 1070 with the UE 100 depending on the QoSinformation for all the QoS flows of the PDU sessions whose UPconnections may be activated and data radio bearers. In an example, theuser plane security may be established.

In an example, if the N2 request may include a MM NAS service acceptmessage, the RAN 105 may forward the MM NAS service accept to the UE100. The UE 100 may locally delete context of PDU sessions that may notbe available in 5GC.

In an example, if the N1 SM information may be transmitted to the UE 100and may indicate that some PDU session(s) may be re-established, the UE100 may initiate PDU session re-establishment for the PDU session(s)that me be re-established after the service request procedure may becomplete.

In an example, after the user plane radio resources may be setup, theuplink data from the UE 100 may be forwarded to the RAN 105. The RAN 105(e.g., NG-RAN) may send the uplink data to the UPF 110 address andtunnel ID provided.

In an example, the (R)AN 105 may send to the AMF 155 an N2 request Ack1105 (e.g., N2 SM information (comprising: AN tunnel info, list ofaccepted QoS flows for the PDU sessions whose UP connections areactivated, list of rejected QoS flows for the PDU sessions whose UPconnections are activated)). In an example, the N2 request message mayinclude N2 SM information(s), e.g. AN tunnel info. RAN 105 may respondN2 SM information with separate N2 message (e.g. N2 tunnel setupresponse). In an example, if multiple N2 SM information are included inthe N2 request message, the N2 request Ack may include multiple N2 SMinformation and information to enable the AMF 155 to associate theresponses to relevant SMF 160.

In an example, the AMF 155 may send to the SMF 160 aNsmf_PDUSession_UpdateSMContext request 1110 (N2 SM information (ANtunnel info), RAT type) per PDU session. If the AMF 155 may receive N2SM information (one or multiple) from the RAN 105, then the AMF 155 mayforward the N2 SM information to the relevant SMF 160. If the UE 100time zone may change compared to the last reported UE 100 Time Zone thenthe AMF 155 may include the UE 100 time zone IE in theNsmf_PDUSession_UpdateSMContext request message.

In an example, if dynamic PCC is deployed, the SMF 160 may initiatenotification about new location information to the PCF 135 (ifsubscribed) by invoking an event exposure notification operation (e.g.,a Nsmf_EventExposure_Notify service operation). The PCF 135 may provideupdated policies by invoking a policy control update notificationmessage 1115 (e.g., a Npcf_SMPolicyControl_UpdateNotify operation).

In an example, if the SMF 160 may select a new UPF 110 to act asintermediate UPF 110 for the PDU session, the SMF 160 may initiates anN4 session modification procedure 1120 to the new I-UPF 110 and mayprovide AN tunnel info. The downlink data from the new I-UPF 110 may beforwarded to RAN 105 and UE 100. In an example, the UPF 110 may send tothe SMF 160, an N4 session modification response 1120. In an example,the SMF 160 may send to the AMF 155, an Nsmf_PDUSession_UpdateSMContextresponse 1140.

In an example, if forwarding tunnel may be established to the new I-UPF110 and if the timer SMF 160 set for forwarding tunnel may be expired,the SMF 160 may sends N4 session modification request 1145 to new(intermediate) UPF 110 acting as N3 terminating point to release theforwarding tunnel. In an example, the new (intermediate) UPF 110 maysend to the SMF 160 an N4 session modification response 1145. In anexample, the SMF 160 may send to the PSA UPF 110-3 an N4 sessionmodification request 1150, or N4 session release request. In an example,if the SMF 160 may continue using the old UPF 110-2, the SMF 160 maysend an N4 session modification request 1155, providing AN tunnel info.In an example, if the SMF 160 may select a new UPF 110 to act asintermediate UPF 110, and the old UPF 110-2 may not be PSA UPF 110-3,the SMF 160 may initiate resource release, after timer expires, bysending an N4 session release request (release cause) to the oldintermediate UPF 110-2.

In an example, the old intermediate UPF 110-2 may send to the SMF 160 anN4 session modification response or N4 session release response 1155.The old UPF 110-2 may acknowledge with the N4 session modificationresponse or N4 session release response message to confirm themodification or release of resources. The AMF 155 may invoke theNamf_EventExposure_Notify service operation to notify the mobilityrelated events, after this procedure may complete, towards the NFs thatmay have subscribed for the events. In an example, the AMF 155 mayinvoke the Namf_EventExposure_Notify towards the SMF 160 if the SMF 160had subscribed for UE 100 moving into or out of area of interest and ifthe UE's current location may indicate that it may be moving into ormoving outside of the area of interest subscribed, or if the SMF 160 hadsubscribed for LADN DNN and if the UE 100 may be moving into or outsideof an area where the LADN is available, or if the UE 100 may be in MICOmode and the AMF 155 had notified an SMF 160 of the UE 100 beingunreachable and that SMF 160 may not send DL data notifications to theAMF 155, and the AMF 155 may informs the SMF 160 that the UE 100 isreachable, or if the SMF 160 had subscribed for UE 100 reachabilitystatus, then the AMF 155 may notify the UE 100 reachability.

An example PDU session establishment procedure depicted in FIG. 12 andFIG. 13. In an example embodiment, when the PDU session establishmentprocedure may be employed, the UE 100 may send to the AMF 155 a NASMessage (or a SM NAS message) comprising NSSAI, S-NSSAI (e.g., requestedS-NSSAI, allowed S-NSSAI, subscribed S-NSSAI, and/or the like), DNN, PDUsession ID, request type, old PDU session ID, N1 SM container (PDUsession establishment request), and/or the like. In an example, the UE100, in order to establish a new PDU session, may generate a new PDUsession ID. In an example, when emergency service may be required and anemergency PDU session may not already be established, the UE 100 mayinitiate the UE 100 requested PDU session establishment procedure with arequest type indicating emergency request. In an example, the UE 100 mayinitiate the UE 100 requested PDU session establishment procedure by thetransmission of the NAS message containing a PDU session establishmentrequest within the N1 SM container. The PDU session establishmentrequest may include a PDU type, SSC mode, protocol configurationoptions, and/or the like. In an example, the request type may indicateinitial request if the PDU session establishment is a request toestablish the new PDU session and may indicate existing PDU session ifthe request refers to an existing PDU session between 3GPP access andnon-3GPP access or to an existing PDN connection in EPC. In an example,the request type may indicate emergency request if the PDU sessionestablishment may be a request to establish a PDU session for emergencyservices. The request type may indicate existing emergency PDU sessionif the request refers to an existing PDU session for emergency servicesbetween 3GPP access and non-3GPP access. In an example, the NAS messagesent by the UE 100 may be encapsulated by the AN in a N2 message towardsthe AMF 155 that may include user location information and accesstechnology type information. In an example, the PDU sessionestablishment request message may contain SM PDU DN request containercontaining information for the PDU session authorization by the externalDN. In an example, if the procedure may be triggered for SSC mode 3operation, the UE 100 may include the old PDU session ID which mayindicate the PDU session ID of the on-going PDU session to be released,in the NAS message. The old PDU session ID may be an optional parameterwhich may be included in this case. In an example, the AMF 155 mayreceive from the AN the NAS message (e.g., NAS SM message) together withuser location information (e.g. cell ID in case of the RAN 105). In anexample, the UE 100 may not trigger a PDU session establishment for aPDU session corresponding to a LADN when the UE 100 is outside the areaof availability of the LADN.

In an example, the AMF 155 may determine that the NAS message or the SMNAS message may correspond to the request for the new PDU session basedon that request type indicates initial request and that the PDU sessionID may not be used for any existing PDU session(s) of the UE 100. If theNAS message does not contain an S-NSSAI, the AMF 155 may determine adefault S-NSSAI for the requested PDU session either according to the UE100 subscription, if it may contain only one default S-NSSAI, or basedon operator policy. In an example, the AMF 155 may perform SMF 160selection and select an SMF 160. If the request type may indicateinitial request or the request may be due to handover from EPS, the AMF155 may store an association of the S-NSSAI, the PDU session ID and aSMF 160 ID. In an example, if the request type is initial request and ifthe old PDU session ID indicating the existing PDU session may becontained in the message, the AMF 155 may select the SMF 160 and maystore an association of the new PDU session ID and the selected SMF 160ID.

In an example, the AMF 155 may send to the SMF 160, an N11 message,e.g., Nsmf_PDUSession_CreateSMContext request (comprising: SUPI or PEI,DNN, S-NSSAI, PDU session ID, AMF 155 ID, request type, N1 SM container(PDU session establishment request), user location information, accesstype, PEI, GPSI), or Nsmf_PDUSession_UpdateSMContext request (SUPI, DNN,S-NSSAI, PDU session ID, AMF 155 ID, request type, N1 SM container (PDUsession establishment request), user location information, access type,RAT type, PEI). In an example, if the AMF 155 may not have anassociation with the SMF 160 for the PDU session ID provided by the UE100 (e.g. when request type indicates initial request), the AMF 155 mayinvoke the Nsmf_PDUSession_CreateSMContext request, but if the AMF 155already has an association with an SMF 160 for the PDU session IDprovided by the UE 100 (e.g. when request type indicates existing PDUsession), the AMF 155 may invoke the Nsmf_PDUSession_UpdateSMContextrequest. In an example, the AMF 155 ID may be the UE's GUAMI whichuniquely identifies the AMF 155 serving the UE 100. The AMF 155 mayforward the PDU session ID together with the N1 SM container containingthe PDU session establishment request received from the UE 100. The AMF155 may provide the PEI instead of the SUPI when the UE 100 hasregistered for emergency services without providing the SUPI. In casethe UE 100 has registered for emergency services but has not beenauthenticated, the AMF 155 may indicate that the SUPI has not beenauthenticated.

In an example, if the request type may indicate neither emergencyrequest nor existing emergency PDU session and, if the SMF 160 has notyet registered and subscription data may not be available, the SMF 160may register with the UDM 140, and may retrieve subscription data andsubscribes to be notified when subscription data may be modified. In anexample, if the request type may indicate existing PDU session orexisting emergency PDU session, the SMF 160 may determine that therequest may be due to handover between 3GPP access and non-3GPP accessor due to handover from EPS. The SMF 160 may identify the existing PDUsession based on the PDU session ID. The SMF 160 may not create a new SMcontext but instead may update the existing SM context and may providethe representation of the updated SM context to the AMF 155 in theresponse. if the request type may be initial request and if the old PDUsession ID may be included in Nsmf_PDUSession_CreateSMContext request,the SMF 160 may identify the existing PDU session to be released basedon the old PDU session ID.

In an example, the SMF 160 may send to the AMF 155, the N11 messageresponse, e.g., either a PDU session create/update response,Nsmf_PDUSession_CreateSMContext response (cause, SM context ID or N1 SMcontainer (PDU session reject(cause))) or anNsmf_PDUSession_UpdateSMContext response.

In an example, if the SMF 160 may perform secondaryauthorization/authentication during the establishment of the PDU sessionby a DN-AAA server, the SMF 160 may select a UPF 110 and may trigger aPDU session establishment authentication/authorization.

In an example, if the request type may indicate initial request, the SMF160 may select an SSC mode for the PDU session. The SMF 160 may selectone or more UPFs as needed. In case of PDU type IPv4 or IPv6, the SMF160 may allocate an IP address/prefix for the PDU session. In case ofPDU type IPv6, the SMF 160 may allocate an interface identifier to theUE 100 for the UE 100 to build its link-local address. For UnstructuredPDU type the SMF 160 may allocate an IPv6 prefix for the PDU session andN6 point-to-point tunneling (based on UDP/IPv6).

In an example, if dynamic PCC is deployed, the may SMF 160 performs PCF135 selection. If the request type indicates existing PDU session orexisting emergency PDU session, the SMF 160 may use the PCF 135 alreadyselected for the PDU session. If dynamic PCC is not deployed, the SMF160 may apply local policy.

In an example, the SMF 160 may perform a session management policyestablishment procedure to establish a PDU session with the PCF 135 andmay get the default PCC Rules for the PDU session. The GPSI may beincluded if available at the SMF 160. If the request type in indicatesexisting PDU session, the SMF 160 may notify an event previouslysubscribed by the PCF 135 by a session management policy modificationprocedure and the PCF 135 may update policy information in the SMF 160.The PCF 135 may provide authorized session-AMBR and the authorized 5QIand ARP to SMF 160. The PCF 135 may subscribe to the IPallocation/release event in the SMF 160 (and may subscribe otherevents).

In an example, the PCF 135, based on the emergency DNN, may set the ARPof the PCC rules to a value that may be reserved for emergency services.

In an example, if the request type in indicates initial request, the SMF160 may select an SSC mode for the PDU session. The SMF 160 may selectone or more UPFs as needed. In case of PDU type IPv4 or IPv6, the SMF160 may allocate an IP address/prefix for the PDU session. In case ofPDU type IPv6, the SMF 160 may allocate an interface identifier to theUE 100 for the UE 100 to build its link-local address. For unstructuredPDU type the SMF 160 may allocate an IPv6 prefix for the PDU session andN6 point-to-point tunneling (e.g., based on UDP/IPv6). In an example,for Ethernet PDU type PDU session, neither a MAC nor an IP address maybe allocated by the SMF 160 to the UE 100 for this PDU session.

In an example, if the request type is in existing PDU session, the SMF160 may maintain the same IP address/prefix that may be allocated to theUE 100 in the source network.

In an example, if the request type in indicates existing PDU sessionreferring to an existing PDU session moved between 3GPP access andnon-3GPP access, the SMF 160 may maintain the SSC mode of the PDUsession, e.g., the current PDU session Anchor and IP address. In anexample, the SMF 160 may trigger e.g. new intermediate UPF 110 insertionor allocation of a new UPF 110. In an example, if the request typeindicates emergency request, the SMF 160 may select the UPF 110 and mayselect SSC mode 1.

In an example, the SMF 160 may perform a session management policymodification procedure to report some event to the PCF 135 that haspreviously subscribed. If request type is initial request and dynamicPCC is deployed and PDU type is IPv4 or IPv6, the SMF 160 may notify thePCF 135 (that has previously subscribed) with the allocated UE 100 IPaddress/prefix.

In an example, the PCF 135 may provide updated policies to the SMF 160.The PCF 135 may provide authorized session-AMBR and the authorized 5QIand ARP to the SMF 160.

In an example, if request type indicates initial request, the SMF 160may initiate an N4 session establishment procedure with the selected UPF110. The SMF 160 may initiate an N4 session modification procedure withthe selected UPF 110. In an example, the SMF 160 may send an N4 sessionestablishment/modification request to the UPF 110 and may provide packetdetection, enforcement, reporting rules, and/or the like to be installedon the UPF 110 for this PDU session. If CN tunnel info is allocated bythe SMF 160, the CN tunnel info may be provided to the UPF 110. If theselective user plane deactivation is required for this PDU session, theSMF 160 may determine the Inactivity Timer and may provide it to the UPF110. In an example, the UPF 110 may acknowledges by sending an N4session establishment/modification response. If CN tunnel info isallocated by the UPF, the CN tunnel info may be provided to SMF 160. Inan example, if multiple UPFs are selected for the PDU session, the SMF160 may initiate N4 session establishment/modification procedure witheach UPF 110 of the PDU session.

In an example, the SMF 160 may send to the AMF 155 anNamf_Communication_N1N2MessageTransfer message (comprising PDU sessionID, access type, N2 SM information (PDU session ID, QFI(s), QoSprofile(s), CN tunnel info, S-NSSAI, session-AMBR, PDU session type,and/or the like), N1 SM container (PDU session establishment accept (QoSRule(s), selected SSC mode, S-NSSAI, allocated IPv4 address, interfaceidentifier, session-AMBR, selected PDU session type, and/or the like))).In case of multiple UPFs are used for the PDU session, the CN tunnelinfo may comprise tunnel information related with the UPF 110 thatterminates N3. In an example, the N2 SM information may carryinformation that the AMF 155 may forward to the (R)AN 105 (e.g., the CNtunnel info corresponding to the core network address of the N3 tunnelcorresponding to the PDU session, one or multiple QoS profiles and thecorresponding QFIs may be provided to the (R)AN 105, the PDU session IDmay be used by AN signaling with the UE 100 to indicate to the UE 100the association between AN resources and a PDU session for the UE 100,and/or the like). In an example, a PDU session may be associated to anS-NSSAI and a DNN. In an example, the N1 SM container may contain thePDU session establishment accept that the AMF 155 may provide to the UE100. In an example, multiple QoS rules and QoS profiles may be includedin the PDU session establishment accept within the N1 SM and in the N2SM information. In an example, theNamf_Communication_N1N2MessageTransfer may further comprise the PDUsession ID and information allowing the AMF 155 to know which accesstowards the UE 100 to use.

In an example, the AMF 155 may send to the (R)AN 105 an N2 PDU sessionrequest (comprising N2 SM information, NAS message (PDU session ID, N1SM container (PDU session establishment accept, and/or the like))). Inan example, the AMF 155 may send the NAS message that may comprise PDUsession ID and PDU session establishment accept targeted to the UE 100and the N2 SM information received from the SMF 160 within the N2 PDUsession request to the (R)AN 105.

In an example, the (R)AN 105 may issue AN specific signaling exchangewith the UE 100 that may be related with the information received fromSMF 160. In an example, in case of a 3GPP RAN 105, an RRC connectionreconfiguration procedure may take place with the UE 100 to establishthe necessary RAN 105 resources related to the QoS Rules for the PDUsession request. In an example, (R)AN 105 may allocate (R)AN 105 N3tunnel information for the PDU session. In case of dual connectivity,the master RAN 105 node may assign some (zero or more) QFIs to be setupto a master RAN 105 node and others to the secondary RAN 105 node. TheAN tunnel info may comprise a tunnel endpoint for each involved RAN 105node, and the QFIs assigned to each tunnel endpoint. A QFI may beassigned to either the master RAN 105 node or the secondary RAN 105node. In an example, (R)AN 105 may forward the NAS message (PDU sessionID, N1 SM container (PDU session establishment accept)) to the UE 100.The (R)AN 105 may provide the NAS message to the UE 100 if the necessaryRAN 105 resources are established and the allocation of (R)AN 105 tunnelinformation are successful.

In an example, the N2 PDU session response may comprise a PDU sessionID, cause, N2 SM information (PDU session ID, AN tunnel info, list ofaccepted/rejected QFI(s)), and/or the like. In an example, the AN tunnelinfo may correspond to the access network address of the N3 tunnelcorresponding to the PDU session.

In an example, the AMF 155 may forward the N2 SM information receivedfrom (R)AN 105 to the SMF 160 via a Nsmf_PDUSession_UpdateSMContextrequest (comprising: N2 SM information, request type, and/or the like).In an example, if the list of rejected QFI(s) is included in N2 SMinformation, the SMF 160 may release the rejected QFI(s) associated QoSprofiles.

In an example, the SMF 160 may initiate an N4 session modificationprocedure with the UPF 110. The SMF 160 may provide AN tunnel info tothe UPF 110 as well as the corresponding forwarding rules. In anexample, the UPF 110 may provide an N4 session modification response tothe SMF 160.

In an example, the SMF 160 may send to the AMF 155 anNsmf_PDUSession_UpdateSMContext response (Cause). In an example, the SMF160 may subscribe to the UE 100 mobility event notification from the AMF155 (e.g. location reporting, UE 100 moving into or out of area ofinterest), after this step by invoking Namf_EventExposure_Subscribeservice operation. For LADN, the SMF 160 may subscribe to the UE 100moving into or out of LADN service area event notification by providingthe LADN DNN as an indicator for the area of interest. The AMF 155 mayforward relevant events subscribed by the SMF 160.

In an example, the SMF 160 may send to the AMF 155, aNsmf_PDUSession_SMContextStatusNotify (release). In an example, ifduring the procedure, any time the PDU session establishment is notsuccessful, the SMF 160 may inform the AMF 155 by invokingNsmf_PDUSession_SMContextStatusNotify (release). The SMF 160 mayreleases any N4 session(s) created, any PDU session address if allocated(e.g. IP address) and may release the association with the PCF 135.

In an example, in case of PDU type IPv6, the SMF 160 may generate anIPv6 Router Advertisement and may send it to the UE 100 via N4 and theUPF 110.

In an example, if the PDU session may not be established, the SMF 160may unsubscribe to the modifications of session management subscriptiondata for the corresponding (SUPI, DNN, S-NSSAI), usingNudm_SDM_Unsubscribe (SUPI, DNN, S-NSSAI), if the SMF 160 is no morehandling a PDU session of the UE 100 for this (DNN, S-NSSAI). In anexample, if the PDU session may not be established, the SMF 160 mayderegister for the given PDU session using Nudm_UECM_Deregistration(SUPI, DNN, PDU session ID).

The 5G system may support CIoT and/or MTC capabilities to supportfrequent small data transmission, infrequent small data transmission.The small data may comprise data payload in the range of e.g., 10, 20,100 bytes or e.g., 1, 10, 20, 100(s) of kilo bytes.

In an example, CIoT features may support infrequent small datatransmissions for at least low complexity, power constrained, low datarate CIoT UEs, and/or the like. In an example, the devices (e.g. utilitymeters, sensors, low power devices, and/or the like) may be mobilethroughout their lifetime.

The end-to-end communications between the CIoT/MTC application in the UEand the CIoT/MTC application in the external network, may utilizeservices provided by the 3GPP system (e.g., 5GS). In an example, acapability server (e.g., a service capability server, SCS, and/or thelike) may provide the end-to-end communications between the CIoT/MTCapplication in the UE and the CIoT/MTC application in the externalnetwork.

The CIoT/MTC application in the external network may be hosted by anapplication server (AS), an application function (AF) and/or the like.In an example, the AS and/or the AF may employ an SCS for additionalvalue added services. The 3GPP system may provide transport, subscribermanagement and other communication services including variousarchitectural enhancements, device triggering via control plane/userplane, data transmission via control plane/user plane, and/or the like.

In an example, device triggering may enable the capability server (e.g.,SCS) to send information to the UE via the 3GPP network to trigger theUE to perform application specific actions. In an example, theapplication specific actions may comprise initiating communication withthe SCS via the control plane, and/or user plane. Device triggering maybe required when an IP address for the UE is not available or reachableby the SCS/AS, or AF.

A device trigger message may comprise information that may enable thenetwork to route the message to the appropriate UE and the UE to routethe message to the appropriate application. In an example, a triggerpayload may comprise the information destined to the application, theinformation to route the information, and/or the like. In an example,the trigger payload, upon the reception by the UE may provideinformation to the application that may trigger application relatedactions. The application in the UE may perform indicated actions, suchas for example to initiate immediate or later communication to theSCS/AS and/or AF, based on the information contained in the triggerpayload.

In an example, device triggering may be subscription based. Thesubscription may provide the information whether a UE is allowed to betriggered by a specific SCS, SCS/AS, AF, and/or the like. In an example,when device triggers are delivered via MT-SMS the serving nodes (e.g.,AMF, SMF, UPF, and/or the like) may provide the service towards aspecific UE based on the UE's subscription for MT-SMS and othersubscription parameters affecting MT-SMS service provision.

In an example, device triggering recall/replace functionality may allowa SCS, SCS/AS, or AF to recall or replace submitted trigger message(s)which are not yet delivered to the UE.

In an example, the 5GS may support functions for high latencycommunication, HLC. HLC may be used to handle mobile terminated (MT)communication with UEs being unreachable while using power savingfunctions e.g. UE power saving mode or extended idle mode DRX dependingon operator configuration. High latency may be the initial response timebefore normal exchange of packets is established. The initial responsetime may be the time it takes before a UE has woken up from its powersaving state and responded to the initial downlink packet(s).

In an example, high latency communication may be handled by an extendedbuffering of downlink data in a UPF, NEF, SMF, AMF, and/or the like. Inan example, extended buffering may be controlled by the AMF, SMF, and/orthe like. The AMF and/or the SMF may ask the UPF to buffer downlink datauntil the UE is expected to wake up from its power saving state.

In an example, if control plane CIoT optimization is used, high latencycommunication may be handled by the buffering of downlink data in theUPF, AMF, SMF and/or the like.

In an example, high latency communication may be handled by notificationprocedures. The SCS/AS or AF may request notification when a UE wakes upfrom its power saving state and sends downlink data to the UE when theUE is reachable. In an example, the notification procedure may beavailable based on monitoring event for UE reachability, monitoringevent for availability after data notification (e.g., DDN) failure,and/or the like.

In an example, the SCS/AS or AF may request a one-time UE reachabilitynotification when it wants to send data to the UE. In an example, theSCS/AS or AF may request repeated availability after DDN failurenotifications where each notification is triggered by a DDN failure i.e.the SCS/AS may send a downlink packet which is discarded by a corenetwork node (e.g., UPF, SMF, AMF) and may trigger the AMF or SMF tosend an event notification to the SCS/AS next time the UE wakes up.

In an example, the length of the power saving intervals used by thenetwork may determine the maximum latency for a UE. An SCS/AS or AF,which has a specific requirement on the maximum latency for UEs itcommunicates with, may provide its maximum latency requirement to thenetwork.

In an example embodiment, a reachability procedure may be employed toreach a UE. Elements of the reachability procedure may be used byservices such as SMS over NAS, data transmission for UEs in power savingmode, and/or the like. The reachability procedure may be employed by UEsthat are in RRC-IDLE, RRC-INACTIVE or RRC-CONNECTED states.

In an example embodiment as depicted in example FIG. 14, a UEreachability notification procedure may be employed.

In an example, during a registration or subscription update procedure, aUDM may inform an AMF of the identities (e.g. FQDNs, NF ID, and/or thelike) of the network functions (NF) that are authorized to requestnotifications on the reachability of the UE via a registration serviceprocedure such as Nudm_UECM_Registration, Nudm_SubscriberData_Updateservice operation, and/or the like.

In an example, if a service-related entity requests the UDM to providean indication regarding UE reachability, the UDM may check that theservice-related entity is authorized to perform this request on thesubscriber associated to the UE. In an example, if the entity is notauthorized, the request may be rejected (e.g. if the requesting entityis recognized as being a valid entity, but not authorized for thatsubscriber) or silently discarded (e.g. if the requesting entity is notrecognized).

In an example, the UDM may store the identity of the service-relatedentity and may set the URRP-AMF parameter to indicate that such requestis received. If the value of URRP-AMF parameter has changed from “notset” to “set”, the UDM may initiate Namf_EventExposure_Subscribe serviceoperation (URRP-AMF) towards the AMF. The UDM may indicate if directnotification to the NF may be used. In an example, the UDM may triggerUE reachability notification request procedure with two different AMFsfor the UE which may be connected to 5G core network over 3GPP accessand non-3GPP access simultaneously. In an example, the UDM may triggerUE reachability notification request procedure with a mobilitymanagement entity, MME.

In an example, the AMF may check that the requesting entity isauthorized to perform the request on the subscriber. In an example, ifthe entity is not authorized, the request may be rejected (e.g. if therequesting entity is recognized as being a valid entity, but notauthorized for the subscriber) or silently discarded (e.g. if therequesting entity is not recognized).

In an example, if the AMF has a MM Context for the user or the UE, theAMF may set URRP-AMF to indicate the need to report to the UDMinformation regarding changes in UE reachability, e.g. when the next NASactivity with that UE is detected.

In an example, if the UE state in the AMF is CM-CONNECTED state, the AMFmay initiate N2 notification procedure with reporting type set to singleRRC-Connected state notification.

In an example embodiment as depicted in example FIG. 15, a UE activitynotification procedure may be employed for reachability of a UE.

In an example, an AMF may receive an (N1) NAS signaling for a UE inCM-IDLE that may imply UE reachability, e.g. a registration request orservice request message from the UE. In an example, AMF may receive an(N2) UE Notification or an (N2) Path Switch Request from the RAN for aUE in CM-CONNECTED state.

In an example, if the AMF has a MM context for the UE and the URRP-AMFis set to report once that the UE is reachable, the AMF may initiate anotification e.g., an Namf_EventExposure_Notify service operation (e.g.,comprising SUPI, UE-Reachable, and/or the like) message to the UDM ordirectly to the NF (if previously indicated to the AMF). The AMF mayclear the corresponding URRP-AMF for the UE.

In an example, when the UDM receives the Namf_EventExposure_Notifyservice operation (SUPI, UE-Reachable) message or Nudm_UECM_Registrationservice for a UE that has URRP-AMF set, the UDM may trigger appropriatenotifications to the NFs (e.g. SMSF or SMS-GMSC, NEF, and/or the like)that have subscribed to the UDM for the reachability notification.

In an example embodiment, 5GS may support small data communication usingan application programming interface (API) corresponding to e.g., T8API, Nm API, and/or the like. The API may support packet transmissionusing IP-based, non-IP based, and/or the like protocols on thesouthbound interface. A messaging function entity (e.g., a network IoTmessaging function, NIMF) may be employed. The NIMF may be an extensionwith an additional role for the 5G network exposure function (NEF), orit may be a new network function dedicated for small data communicationfor IoT/CIoT. In an example, the NIMF may be a new standalone networkfunction entity.

The NIMF or NEF for small data communication may be located in theoperator domain.

In an example, the NIMF may support a northbound Nm interface. On thenorthbound interface, the Small data network function may support forexample the T8 non-IP data delivery NIDD Nm API, unstructured Nm API,and/or the like.

In an example, the NIMF may support a southbound N6m interface. Thesouthbound interface may enable small data communication with differenttypes of CIoT devices using different protocol stacks. In an example,the southbound interface has a PDU session layer which may support PDUSessions of different types e.g., IPv4, IPv6, Ethernet, unstructured,non-IP, and/or the like. In an example, on top of the PDU session layerhigher layer IoT protocols may be employed and supported towards the UE,e.g. Lightweight machine to machine, LWM2M, non-IP data deliveryreliable data service, NIDD RDS, and/or the like.

The NIMF or NEF may store and forward small data. The southboundprotocols may be terminated in the NIMF or NEF. The NIMF may map or actas proxies between the northbound and southbound protocols.

In an example, the NIMF may support lawful intercept LI (message based),charging (message based, i.e. number of CIoT messages), and/or the like.

In an example, if encryption protocols (e.g., datagram transport layersecurity (DTLS)) are employed as part of the southboundinterface/connection, the NIMF may offer LI of unencrypted data.

In an example, when a UE establishes a PDU Session, as part of theregistration procedure, or attach procedure, for which DNN configurationindicates small data communication to be used, then the SMF may initiatea connection towards the NEF or NIMF corresponding to the NEF ID or NIMFID for the DNN.

In an example as depicted in example FIG. 16, the UE may request theestablishment of a PDU Session wherein an N4 session establishment inthe UPF may be performed as part of the PDU session establishment.

In an example, a connection may be established between the UPF and theNIMF for the PDU Session. The NIMF may store the IP address of the PDUSession, the IMSI and the External ID or MSISDN of the UE, the IPversion to use (IPv6, IPv4 or Unstructured), and PCO. In an example, forunstructured PDU session when point-to-point tunneling based on UDP/IPencapsulation is used, the UPF may store the forwarding IP address tothe selected NIMF. For PDU sessions of type IP, the forwarding to theNIMF may be controlled by IP destination address used at the higherlayer protocol (e.g., LWM2M).

In an example, uplink and downlink data transmissions may take placeusing IP data or Unstructured (Non-IP) data depending on the PDU Sessiontype used by the UE.

In an example, when PDU Session release is initiated, the connectionbetween the UPF and the NIMF may be released. The NIMF may remove thestored IP address of the PDU session, and may mark the UE as inactive,and may close the connection for (small) data transmissions to/from theUE. The N4 Session may be released in the UPF.

In an example embodiment as depicted in example FIG. 17, the 5GS maysupport unstructured data transmission or non-IP data transmission(NIDD). The UE may support a NIDD client, for delivery of Unstructured(Non-IP) data. The SCS/AS or AF may send and receive messages to/from agiven UE identified by an External Identifier, MSISDN, and/or the like.The UE may have an Unstructured PDU session activated and the message onthe Nm or T8 API may be mapped to DL non-IP data PDU or from UL non-IPdata PDU delivered to/from the UE. In an example, for the direct modelcase, the DL and UL data PDUs may be transmitted directly between theUPF and the SCS/AS.

In an example, an SCS/AS or AF may send a MT submit request with smalldata using T8 API, Nm API, and/or the like to a NEF or a NIMF.

The NIMF/NEF may determine the UE based on established connections andthe external identifier or MSISDN included in the MT submit request. TheNIMF may perform authorization and quota checks. If there is noestablished connection corresponding to the external identifier orMSISDN, the NIMF may send a MT submit response with appropriate errorcause value. In an example, if there is no established connectioncorresponding to the external identifier or MSISDN, the NIMF/NEF mayperform device triggering towards the UE to establish a connection.

The NIMF may sends a DL data PDU towards the UE using the IP addressassociated with the connection established by the UE. If the NIMFexpects no acknowledgement on the message with the DL data PDU, the NIMFmay sends a MT submit response to the SCS/AS informing that anunacknowledged transmission to the UE has been made.

In an example, the UE may send an UL data PDU to the NIMF. The NIMF maydetermine if the received UL data is an acknowledgement of the DL data.If the UL data PDU is an acknowledgement, the NIMF may send a MT SubmitResponse to the SCS/AS informing that an acknowledged transmission tothe UE has been made.

In an example embodiment, a reliable data service (RDS) may be used bythe UE and NEF for reliable (small) data delivery of unstructured PDU.The RDS may provide a mechanism for the NEF to determine if the data wassuccessfully delivered to the UE and for the UE to determine if the datawas successfully delivered to the NEF. In an example, when a requestedacknowledgement is not received, the reliable data service mayretransmit the packet. In an example, the RDS may employ NAS transportbetween the UE and the AMF for small data delivery. This may apply toboth 3GPP and non-3GPP accesses. In an example, the RDS may requiresupport for the AMF determining the NEF for a UE. In an example, the NEFmay support subscription checking and actual transmission of MO/MT smalldata delivery by the NEF to the AF/UE. In an example, the RDS maysupport MO/MT small data delivery for both roaming and non-roamingscenarios, unstructured PDU, and/or API exposure for reliable dataservice towards 3rd party application providers.

In an example, during a registration procedure, a UE may provide RDSsupported indication over NAS signaling indicating the UE's capabilityfor support of RDS. In an example, the RDS supported indication mayindicate whether the UE may support reliable small data delivery overNAS via 3GPP access or via both 3GPP and non-3GPP access. If the corenetwork supports RDS functionality, the AMF may include RDS supportedindication to the UE, and whether RDS delivery over NAS via 3GPP accessor via both the 3GPP and non-3GPP access is accepted by the network.

In an example, RDS packets may be transmitted over NAS without the needto establish data radio bearers, via NAS transport message, which cancarry RDS payload. PDU session establishment may not be needed. The UEand network may support RDS protocol. In an example, when the RDS isenabled, a protocol may be used between the end-points, e.g., betweenthe UE and the NEF. The protocol may employ an RDS header to identify ifthe packet requires no acknowledgement, requires an acknowledgement, oris an acknowledgment and to allow detection and elimination of duplicatePDUs at the receiving endpoint. In an example, port numbers in theheader may be used to identify the application on the originator and toidentify the application on the receiver.

An example FIG. 18 depicts data transmission over NAS (e.g., MM-NAS andSM-NAS).

An example FIG. 19 depicts a reliable data service via control plane toan SCS/AS via an NEF. The scenarios depicted in FIG. 19 employ datatransmission through AMF and through AMF and SMF.

An example FIG. 20 depicts data transmission via user plane from awireless device to a data network and to a SCS/AS or an AF. The datatransmission may employ an NEF network function with a data transmissionsupport functionality.

An example FIG. 21 depicts an example of a network function registrationwith an NRF and configuration with an OAM. The network function may be aUPF as depicted in FIG. 21. The network function may be an NEF, NIMF,and/or the like.

5GS may support (small) data transmission for cellular Internet ofthings (CIoT) applications. Data transmission may be via control planeand/or user plane (e.g. control plane network nodes and interfacesand/or user plane network nodes and interfaces). CIoT optimizations mayrequire the network elements and network functions to support the CIoTdata transmission functionality, CIoT enabling features, and/or thelike. When a network entity and/or an external network entity (e.g.,third party application, application function, application server,service capability server, and/or the like) requests to send data orpackets to a wireless device and/or an application running on a wirelessdevice, the network entity may send a request to a network exposurefunction (NEF) to request a data transmission via the user plane and/orthe control plane. If a user plane data transmission is requested and/orselected, and the network exposure function does not have an address ofUPF that serves the wireless device (e.g. UE) and is capable ofsupporting a requested PDU session, the NEF may respond to therequesting network entity with an error cause message indicating afailure, a data transmission error, and/or the like and may stop datatransmission. An existing signaling mechanism for a CIoT datatransmission may result in increased communication failures when datatransmission associated with a CIoT functionality is initiated. Anexisting signaling mechanism for a CIoT data transmission may result inan increased packet loss rate when data transmission associated with aCIoT functionality is initiated. An existing signaling mechanism for aCIoT data transmission may result in a longer communication delay whendata transmission associated with a CIoT functionality is initiated.Existing technologies for a CIoT data transmission may cause inefficientsignaling between network nodes. Existing technologies for a CIoT datatransmission may degrade reliability of communication network systems.

Example embodiments provide reliable CIoT related services for awireless device by enabling an NEF (and/or NIMF) to get information ofuser plane network nodes (e.g. UPF and/or SMF) supporting a CIoT datatransmission from a network repository function (NRF). In an example,when receiving a data transmission request (e.g. small datatransmission, CIoT data transmission), an NEF may request UPFinformation to an NRF. In response to the UPF information request, theNRF may respond with an identifier and/or an address of a UPF thatsupports a CIoT data transmission. Based on the identifier and/or theaddress of the UPF, the NEF may send a small data transmissionindication to the UPF supporting the CIoT data transmission. Exampleembodiments reduce a failure rate and/or a communication delay of a CIoTdata transmission by supporting a signaling mechanism for a NEF (and/oran NIMF) to get UPF information for a CIoT service.

In an example embodiment as depicted in example FIG. 22 and FIG. 23, afirst network element may receive from a second network element, a firstrequest message for delivery of one or more packets to a wirelessdevice, a UE. The first request message may comprise the one or morepackets, an identifier for the wireless device, and/or the like.

In an example, the first request message may be from a servicecapability server (SCS), an application server (AS), an applicationfunction (AF), and/or the like. In an example, the first network elementmay be a network exposure function (NEF), a messaging function, anetwork Internet of things (IoT) messaging function (NIMF), and/or thelike. In an example, the second network element may be the SCS, the AS,the AF, and/or the like. The first request message, may indicate arequest for delivery of the one or more packets to the wireless device(or activate the delivery of the one or more packets to the UE), the UE.The one or more data packets may be non-IP data, IPv4 packets, IPv6packets, unstructured data, Ethernet packet, and/or the like. In anexample, the first request message may trigger establishment of a PDUsession of type non-IP, IPv4, IPv6, unstructured, Ethernet, and/or thelike. The first request message may be for a data transmission over userplane, data transmission over control plane and/or the like. In anexample, the first network element may decide if the one or more packetsto be delivered over control plane or user plane. In an example, thetransmission of the one or more packets may utilize a control planecellular IoT (CIoT) optimization, a user plane CIoT optimization, and/orthe like. In an example, the first request message may further indicatea request of at least one of a small data transmission, a CIoToptimization based data transmission, a type of the one or more packets(e.g. a service type associated with the one or more packets, a packettype of small size data), a QoS requirement of the one or more packets(e.g. latency, throughput, packet loss rate, delay, and/or the like), atype of a PDU session (e.g., a type of the requested PDU session (e.g.,unstructured, non-IP, IPv4, IPv6)), and/or the like.

In an example, the first request message may comprise an externalidentifier of the UE (e.g., MSISDN), a transaction reference identifierthat may be associated with the transactions between the first networkelement (e.g., NEF, NIMF, and/or the like), and the second networkelement (e.g., SCS/AS, AF, and/or the like), the one or more datapackets, data transmission configuration parameters, latency, priorityinformation, PDU session establishment option, and/or the like.

In an example embodiment, the interaction between the first networkelement (e.g. NEF, NIMF) and the second network element (e.g. SCS, AS,AF) may be over an application programming interface (API). In anexample, the API (e.g., a northbound API) may be an interface betweenthe AS, SCS/AS, and/or AF, (e.g., either in a mobile operator's networkor external to it—operated by a third party) and the 3GPP system viaspecified functions in a mobile operator's network. In an example, APIsma enable interaction at the application layer.

In an example, support of data communication (e.g., small datatransmission) using an API may corresponding to a T8 API (e.g., the APIbetween the SCS/AS and a SCEF), an API between the NIMF/NEF and theSCS/AS. In an example, the NIMF may support an API (e.g., Nm API) andmay support transmission using IP-based, non-IP based, and/or the likeprotocols on the southbound interface towards the 3GPP network. In anexample, the NIMF may be an extension with an additional role for the 5GNetwork Exposure Function (NEF), or it may be a new NF dedicated forsmall data communication, or it may be a standalone networkfunction/entity.

In an example, the first network element may determine that the firstrequest message for delivery of the one or more packets is for CIoT datatransmission. The determination may be based on a type of request (e.g.,non-IP, unstructured data, and/or the like) or based on an indicationreceived from the second network element (e.g., SCS/AS). In an example,a configuration may be required in order to reach a group of wirelessdevices or the wireless device and send receive the one or more packetsfor CIoT. In an example, the SCS/AS may send a configuration request(e.g., comprising external identifier or MSISDN, SCS/AS or AFidentifier, data transmission duration, Nm API destination address,requested action, a PDU session establishment option field, reliabledata service configuration, and/or the like) message to the NEF/NIMF.The PDU session establishment option field may be employed to indicatewhat the NEF/NIMF needs to do if the UE has not established a PDUsession and mobile terminating packet transmission (e.g., unstructured,non-IP data, and/or the like) needs to be sent. In an example, the PDUsession establishment option field may employ a value to indicate to theNEF/NIMF to wait for the UE to establish a PDU session, to respond withan error cause, or to send a device trigger. When the PDU sessionestablishment option field is included in the configuration message anda value is assigned to the PDU session establishment option field, theNEF/NIMF may use the value as a default preference from the SCS/AS whenhandling mobile terminating (MT) unstructured, non-IP packets, and/orthe like associated with a data transmission (e.g., non-IP,unstructured, and/or the like) connection. In an example, reliable dataservice configuration may be a parameter that may be employed toconfigure a reliable data service including addresses, identifiers, portnumbers, and/or the like for originator application(s) and receiverapplication(s).

In an example, in response to receiving the first request message, theNEF/NIMF may trigger the wireless device, the UE. The NEF may check thatthe SCS/AS or the AF is authorized to send trigger requests and/or thatthe AF has not exceeded its quota or rate of trigger submission via theNEF (e.g., over Nnef). If this check fails, the NEF may send anNnef_Trigger_Request response with a cause value indicating a reason fora failure condition and a flow associated with the first request messagemay stop. In an example, the NEF may invoke a query to a UDM (e.g.,Nudr_UDM_Query) with a generic public subscription identifier (GPSI)and/or an identifier of the SCS/AS or an identifier of the AF) todetermine if the SCS/AS or the AF is authorized to trigger the UE. In anexample, the query may resolve the GPSI to a subscriber permanentidentifier (SUPI) and may retrieve a related routing information (e.g.,serving node identities) that may be stored in a user data repository(UDR). In an example, the routing information may comprise serving nodeinformation for the UE, e.g., serving AMF, serving SMF, and/or the like.In an example, the UDM/UDR may provide a Nudr_UDM_Query response (e.g.,comprising: the SUPI and/or MSISDN and related routing informationincluding the serving node(s) identities, the cause, and/or the like).UDR policy may influence which serving node identities may be returned.In an example, if the cause value indicates the AS/AF is not allowed tosend a trigger message to the UE, there is no valid subscriptioninformation, absent subscriber is received from UDR and/or the validityperiod of this trigger message is set to zero, the NEF may send anNnef_Trigger_Request response with a cause value indicating a reason forthe failure condition.

In an example, the NEF/NIMF may trigger the UE (e.g., to perform a UEtriggered PDU session establishment) by invoking a device triggeringprocedure to the UE via control plane and/or user plane. In an example,the NIMF/NEF (e.g., via the SMF, AMF and/or the like) may send a devicetrigger message to application(s) on the UE. The device trigger messagemay comprise a payload (e.g., a trigger payload). The payload may beincluded in the device trigger message. The device trigger message maycomprise information that may be employed by the UE to determine whichapplication may trigger a PDU session establishment request. Based onthe information from the payload, the application(s) on the UE side maytrigger a PDU session establishment procedure. In an example, the devicetrigger message may comprise information that may enable a network toroute the device trigger message to the UE and may enable the UE toroute the message to the SCS/AS or AF. The payload (e.g., the triggerpayload) may be the information destined to the application, and mayfurther comprise information to route the trigger payload. Theapplication in the UE may perform actions indicated by the triggerpayload when the trigger payload is received at the UE. In an example,the action may include initiation of immediate or later communicationwith the application server, SCS/AS or AF based on the elements of thetrigger payload. In an example, the information may be related to thePDU session establishment procedure if the PDU session is not alreadyestablished. In an example, the NEF/NIMF may invoke the devicetriggering procedure to trigger the UE via the SMF, AMF, SMSF, and/orthe like. The NEF/NIMF may invoke the device triggering procedure to theUE via the UPF by sending the data notification and the UPF may triggerthe UE via the SMF, the AMF, and/or the like.

The first network element may determine that the UPF network selectionis required. The UPF network element selection may be in response todetermining that a UPF network element address may be required fortransmission of the one or more packets. In an example, the firstnetwork element may send the first message in response to determiningthat the first network element requires to select a UPF supporting CIoT.In an example embodiment, the first network element (e.g. NEF, NIMF) maysend, to a network repository function (NRF) (or a repository networkelement, network function, a user data management (UDM) and/or thelike), a first message indicating a request of a user plane function,UPF network element selection for a cellular internet-of-things (CIoT)packet transmission. In an example, the first message may comprise atleast one of an identifier of the first network element, a first singlenetwork slice selection assistance information (S-NSSAI) associated withthe CIoT packet transmission, a PDU session type (e.g., unstructured,Ethernet, non-IP, IPv4, IPv6, and/or the like) associated with the CIoTpacket transmission, a DNN associated with the first network element, aUE identifier of the wireless device (e.g. associated with the request),and/or the like.

In an example, the S-NSSAI may indicate a network slice that the one ormore packet is associated with. The S-NSSAI may indicate that aselection of a UPF network element may require an S-NSSAI considerationto support compatible network functionalities, e.g., slice type, slicedescription, slice isolation constraints, and/or the like.

In an example, the first message may indicate that the UPF networkelement selection for the (CIoT) packet transmission may be a networkfunction discovery procedure. The network function discovery proceduremay be for the UPF network element or a network element that supportstransmission of the one or more packets for CIoT, the small datatransmission, the CIoT optimization based data transmission, and/or thelike. The network function discovery procedure for the UPF networkelement may comprise an information element (IE) indicating that supportof the CIoT packet transmission may be required by the UPF networkelement.

In an example, the first message may be part of a network function (NF)discovery procedure or a NF service discovery procedure (e.g., aNnrf_NFDiscovery service) via an NRF. In an example, a NF (e.g. NEFand/or NIMF) may send a discovery request message (e.g.,Nnrf_NFDiscovery_Request) to the NRF and receive a discovery responsemessage (e.g., Nnrf_NFDiscovery_Response) from the NRF.

The NF discovery procedure and/or NF service discovery procedure mayenable a NF (e.g., the NEF/NIMF) to discover a set of NF instance(s)with a NF service, a NF capability, a NF type, and/or the like.

In an example, in order to enable access to a requested NF type or NFservice (e.g., the UPF supporting the NF type or the NF service), arequester NF (e.g., the NEF/NIMF) may invoke the NF discovery procedureor the NF service discovery procedure by providing, to the NRF (e.g. viathe first message), a type of the NF or a specific service (e.g.,service type), and/or other service parameters e.g., slicing relatedinformation to discover a NF. The requester (e.g. the NF) may attempt todiscover a network node (e.g. UPF, NEF, NIMF, SMF, PCF, UE locationreporting, and/or the like) supporting the type of the NF or thespecific service. In an example, in response to receiving the firstmessage, the NRF may provide an IP address or a fully qualified domainname (FQDN) or an identifier of relevant services and/or NF instance(s)(e.g. an instance of the UPF) to the requester NF for NF selection. Inan example, based on the received information (e.g., the IP address orthe FQDN of the NF) from the NRF, the requester NF may select one ormore NF instance(s) (e.g., an instance of the UPF network element thatmay provide CIoT data transmission, device triggering, and/or the like)that may be able to provide the requested NF service.

In an example, the first message may be a Nnrf_NFDiscovery_Requestmessage. The Nnrf_NFDiscovery_Request message may comprise NF servicename(s) (e.g., UPF, user plane CIoT data transmission, CIoT/MTC datatransmission, and/or the like), NF type of a target NF (e.g., the UPFNF), a NF type of the NF service consumer (e.g., the first networkelement NF type, i.e., the NEF, NIMF), S-NSSAI(s), an identifier of atarget NF/NF service PLMN (e.g., UPF PLMN ID), serving PLMN ID, anidentifier of the service consumer NF (e.g., the NEF/NIMF ID, the SMFID, and/or the like), and/or the like. In an example, in response to thefirst message, the NRF may provide to the first network element (e.g.the NEF/NIMF), the IP address or FQDN of the expected NF instance(s)(e.g. UPF).

In an example embodiment, the first network element, may receive fromthe NRF in response to the first message, a second message. The secondmessage may comprise at least one of an identifier of the UPF networkelement, an address of the UPF network element, a second S-NSSAI thatthe UPF network element may support, and/or the like.

In an example, the second message may be part of the network function(NF) discovery procedure or the NF service discovery (e.g., aNnrf_NFDiscovery service) procedure. The second message may be anNnrf_NFDiscovery_Response message. In an example, the second S-NSSAI maybe the first S-NSSAI, or an S-NSSAI (e.g., the second S-NSSAI) with thesame or compatible service type or service description as the firstS-NSSAI. In an example, the NRF may provide a set of candidate NFs(e.g., UPFs) to the first network element and the first network elementmay select the UPF network element/function based on the received set ofcandidates NFs and the elements of the first request message and/or thefirst message. In an example the first network element may select one ofthe set of candidate NFs for the one or more packets. In an example, theNRF may select the UPF network element based on the elements of thefirst message. In an example, the first network element (e.g., the NEF,the NIMF, and/or the like) may select the UPF network element based onthe elements of the first message and/or the second message.

In an example embodiment, the first network element may send to the UPFnetwork element, a third message based on the elements of the secondmessage. The third message may comprise the identifier of the firstnetwork element (e.g., NIMF ID/FQDN, NEF ID/FQDN, and or the like), theone or more packets, the identifier for the wireless device (e.g., apermanent equipment identifier, a mobile station internationalsubscriber directory number, MSISDN, a SUPI, an international mobileequipment identity, IMEI, an identifier of the UE, and/or the like),and/or the like. In an example, the permanent equipment identifier (PEI)may be defined for a 3GPP UE accessing a 3GPP 5G system. The PEI mayemploy different formats for different UE types and use cases. The UEmay present the PEI to the 5GS network together with an indication of aformat for the PEI. If the UE supports at least one 3GPP accesstechnology, the UE may be allocated a PEI in a format of an IMEI.

If unstructured PDU type is supported by the UPF (e.g. the UPF networkelement), an SMF may allocate an IPv6 prefix for the PDU session and fora point-to-point tunneling between the NEF/NIMF or a DN associated withthe NEF/NIMF (e.g., N6 or N6m point-to-point tunneling). In an example,the point-to-point tunneling may be based on UDP/IP encapsulation. In anexample, the UPF may map the addressing information (IP address, portnumber, and/or the like) between the UPF and the NEF/NIMF, or betweenthe UPF and the DN, to a PDU session related information (e.g., a PDUsession identifier). In an example, when point-to-point tunneling basedon UDP/IPv6 is used, IPv6 prefix allocation for PDU sessions may beperformed locally by a (H-)SMF. In an example, the UPF may act as atransparent forwarding node for payload between the UE and a destinationnode in the DN., e.g., for uplink, the UPF may forward unstructured PDUsession type data to the destination node in the data network or theNEF/NIMF over a point-to-point tunnel (e.g., N6, N6m, and/or the like)using UDP/IPv6 encapsulation, or for downlink, the NEF/NIMF or the DNmay send the unstructured PDU session type data using UDP/IPv6encapsulation with an IPv6 address of the PDU session and a 3GPP definedUDP port for unstructured PDU session type data. The UPF acting as PDUsession anchor may decapsulate (i.e. remove the UDP/IPv6 headers)received data (e.g., the one or more packets encapsulated with the IPv6address of the PDU session) and may forward the received data identifiedby the IPv6 prefix of the PDU session for delivery to the UE.

In an example embodiment as depicted in FIG. 22 and FIG. 23, the firstnetwork element may send to the UPF network element, a fourth messageindicating a data notification (e.g., a downlink data notification)based on the elements of the second message. The fourth message maycomprise the identifier of the first network element (e.g., NIMFID/FQDN, NEF ID/FQDN, and or the like), the identifier for the wirelessdevice (e.g., a permanent equipment identifier, mobile stationinternational subscriber directory number, MSISDN, SUPI, internationalmobile equipment identity, IMEI, UE identifier, and/or the like), and/orthe like. In an example, the permanent equipment identifier (PEI) may bedefined for the 3GPP UE accessing the 5G system. The PEI may employdifferent formats for different UE types and use cases. The UE maypresent the PEI to the network together with an indication of the PEIformat being used. If the UE supports at least one 3GPP accesstechnology, the UE may be allocated a PEI in a format of an IMEI. In anexample the fourth message may further comprise device triggeringpayload for the UE, the PDU session establishment option field and/orthe like. In an example, the UPF may send the data notification to theSMF network element via N4, and may employ N4 related procedures, an N4association setup, an N4 association modification and/or the like.

In an example embodiment, in response to receiving the third messageand/or the one or more packets for the wireless device, the UE, the UPFmay send a data notification to the SMF indicating an arrival of packetsfor the wireless device, the UE. In an example embodiment, the UPF maybuffer the one or more data packets and send the data notification tothe SMF. In an example, in response to receiving the data notification,a network triggered PDU session establishment procedure may beperformed. In an example, the UPF may trigger the UE to e.g., perform aPDU session establishment, a UE triggered PDU session establishment,and/or the like, by invoking the device triggering procedure to the UEvia control plane and/or user plane. In an example, the UPF may send thedevice trigger message (e.g., via the SMF, AMF and/or the like) toapplication(s) on the UE. The device trigger message may comprise thepayload (e.g., the trigger payload). The payload may be included in thedevice trigger message. The device trigger message may compriseinformation that may be employed by the UE to determine whichapplication may trigger the PDU session establishment request. Based onthe information from the payload, the application(s) on the UE side maytrigger the PDU session establishment procedure. In an example, thedevice trigger message may comprise information that may enable thenetwork to route the device trigger message to the UE and may enable theUE to route the message to the SCS/AS and/or the AF.

In an example, when the UPF network element receives the one or morepackets (e.g., downlink data) for a PDU session and/or the wirelessdevice, and there may be no (R)AN tunnel information stored in the UPFnetwork element for the PDU session, the UPF network element may bufferthe one or more packets. In an example, the buffering may be based on abuffer timer value and/or a packet count value. The buffer timer value(e.g., the duration of the buffering) may indicate the duration ofbuffering of the one or more packets at the UPF. In an example, the UPFmay buffer the one or more packets until the PDU session establishmentis successful.

In an example embodiment, the first network element (e.g., the NEF,and/or the NIMF) may buffer the one or more packets and send a datanotification (e.g., a downlink data notification to the UPF networkelement. In an example, buffering at the NEF/NIMF may be based on abuffer timer value and/or a packet count value. The buffer timer value(e.g., the duration of the buffering), may indicate the duration ofbuffering of the one or more packets at the UPF. In an example, the UPFmay buffer the one or more packets until the PDU session establishmentis successful (e.g., the UPF notifies the NEF/NIMF that the PDU sessionestablishment is successful). In an example, the SMF may notify theNEF/NIMF that the PDU session establishment is successful and theNEF/NIMF may send the buffered one or more packets to the UPF networkelement/function.

In an example embodiment as depicted in FIG. 21, when a new UPF isinstantiated or deployed, the new UPF (e.g., the UPF network element)may register itself with the NRF or an OAM. The UPF network element maysend a sixth message indicating that the UPF network element may supportthe CIoT packet transmission, transmission of the one or more packetsfor CIoT, the small data transmission, the CIoT optimization based datatransmission, and/or the like. In an example, the sixth message maycomprise at least one of a network function profile of the UPF networkelement, an identifier of the UPF network element, the second S-NSSAIthat the UPF network element may support, a DNN associated with the UPF,and/or the like. In an example, the NRF may be configured by an OAM withinformation on available UPF(s) or the UPF may register itself onto theNRF. In an example, the NRF may receive from the UPF network element,the sixth message. In an example, the sixth message may comprise aninformation element indicating that user plane CIoT optimization, userplane CIoT packet transmission, transmission of the one or more packetsfor CIoT, the small data transmission, the CIoT optimization based datatransmission, and/or the like may be supported by the UPF networkelement. In an example, the sixth message may further comprise anidentifier of the UPF network function/element, a capability informationof the UPF network function, a traffic routing capability of the UPFnetwork function, a network function type of the UPF network function,an IP address (e.g., IPv4, and/or IPv6) of the UPF network function, afully qualified domain name (FQDN) of the UPF network function, aprofile of the UPF network function, a list of supported S-NSSAIsassociated with the UPF network function, and/or the like. In anexample, the profile of the UPF network function may be employed todescribe the characteristics of a UPF network function instance. Whenthe UPF NF instance is instantiated, the associated UPF NF profile maybe generated and stored on the UPF NF instance. During a serviceregistration procedure, the UPF NF profile may be registered and storedon the NRF. The profile of the UPF network function may comprise a typeof the UPF NF, an FQDN and/or IP address of the UPF NF instance, networkslice related identifier(s) e.g. S-NSSAI, network slice instanceidentifier (NSI ID), UPF NF capacity information, permissions,authorization information, and/or the like.

In an example, in response to receiving the one or more packets, thefirst network element may determine that a SMF network selection isrequired. The SMF network element selection may be in response todetermining that a SMF network element address may be required fortransmission for triggering the wireless device may be required. In anexample embodiment as depicted in FIG. 24 and FIG. 25, the first networkelement may send to a network repository function (NRF) (or a repositorynetwork element, a user data management (UDM), and/or the like), a ninthmessage indicating a request of a session management function(SMF)network element selection for a cellular internet-of-things (CIoT)packet transmission. In an example, the ninth message may comprise atleast one of an identifier of the first network element, a first singlenetwork slice selection assistance information (S-NSSAI) associated withtransmission of the one or more packets, a parameter indicating CIoTpacket transmission, a PDU session type (e.g., unstructured, Ethernet,non-IP, IPv4, IPv6, and/or the like) associated with the CIoT packettransmission, a DNN associated with the first network element, and/orthe like. The first network element may determine that selection of aSMF and/or a UPF network element may be required. The determination thatthe UPF network element selection is required, may be in response to thedetermining that a UPF network element address may be required fortransmission of the one or more packets. The determination that the SMFnetwork element selection is required may be in response to determiningthat a SMF network function for triggering the wireless device may berequired. In an example, the first network element may send the ninthmessage in response to determining that the first network elementrequires to select a UPF and/or SMF that support user plane CIoToptimization, user plane CIoT packet transmission, transmission of theone or more packets for CIoT, the small data transmission, the CIoToptimization based data transmission, and/or the like. In an example,the NEF/NIMF may select an AMF for invoking the device triggeringprocedure to triggering the wireless device, and may send the ninthmessage to the NRF and request selection of an AMF supporting CIoToptimization and device triggering functionality.

In an example, the S-NSSAI may indicate a network slice that the one ormore packets, and/or the first network element is associated with. TheS-NSSAI may indicate that a selection of a UPF/SMF network element mayrequire the S-NSSAI consideration to support compatible networkfunctionalities e.g., slice type, slice description, slice isolationconstraints, and/or the like.

In an example, the ninth message may indicate that the UPF/SMF networkelement selection for the CIoT packet transmission may be a networkfunction discovery procedure. The network function discovery proceduremay be for selection of a SMF network element. The network functiondiscovery for the SMF network element may comprise an informationelement (IE) indicating that support of CIoT packet transmission may berequired by the SMF network element.

In an example, the ninth message may be part of the network function(NF) discovery procedure or the NF service discovery procedure (e.g., aNnrf_NFDiscovery service).

In an example embodiment, the first network element, may receive fromthe NRF in response to the ninth message, a tenth message comprising atleast one of an identifier of the SMF network element, an address of theSMF network element, a second S-NSSAI that the SMF network element maysupport, and/or the like.

In an example, the tenth message may be part of the network function(NF) discovery procedure or the NF service discovery (e.g., aNnrf_NFDiscovery service) procedure. The second message may be anNnrf_NFDiscovery_Response message. In an example, the second S-NSSAI maybe the first S-NSSAI, or an S-NSSAI (e.g., the second S-NSSAI) with thesame or compatible service type or service description as the firstS-NSSAI. In an example, the NRF may provide a set of candidate NFs(e.g., SMFs) to the first network element and the first network elementmay locally select the SMF network element/function based on thereceived set of candidates and the elements of the first request messageand/or the tenth message. In an example, the NRF may select the SMFnetwork element based on the elements of the ninth message. The set ofcandidate NFs may support the CIoT packet transmission associated withthe one or more packets. In an example, the first network element (e.g.,the NEF, the NIMF, and/or the like) may select the SMF network elementbased on the elements of the ninth message and/or the tenth message.

In an example, the NIMF/NEF may buffer the one or more data packets. Inan example, the buffering at the NEF/NIMF may be based on a buffer timervalue and/or a packet count value. The buffer timer value (e.g., theduration of the buffering), may indicate the duration of buffering ofthe one or more packets at the NEF/NIMF. In an example, the UPF maybuffer the one or more packets until the PDU session establishment issuccessful and (e.g., the UPF notifies the NEF/NIMF that the PDU sessionestablishment is successful). In an example, the SMF may notify theNEF/NIMF that the PDU session establishment is successful and theNEF/NIMF may send the one or more packets to the UPF networkelement/function.

In an example embodiment, the first network element may send to the SMFnetwork element, an eleventh message indicating a data notification forthe wireless device. The eleventh message may comprise the identifier ofthe first network element, the identifier for the wireless device,and/or the like. In an example, the SMF may select the UPF networkelement based on the elements of the ninth message and the tenthmessage. In an example, the SMF may select the UPF network elementlocally or via the NRF by the network function discovery procedure.

In an example embodiment, the SMF may select the UPF and send a seventhmessage indicating an acknowledgment to the data notification receivedfrom the first network element, the NEF/NIMF e.g., the eleventh message.In an example, the seventh message may comprise the identifier of theUPF network element, an address of the UPF network element, the secondS-NSSAI that the UPF network element supports, and/or the like.

In an example, embodiment, the first network element may send an eighthmessage to the UPF network element based on the elements of the seventhmessage. In an example, the eighth message may comprise the one or morepackets, the identifier for the wireless device, the UE, and/or thelike. In an example, the first network element may buffer the one ormore data packets for a duration of a timer value and send the one ormore data packets upon expiry of the timer to the UPF network element orwhen the PDU session establishment is successful. In an example, the SMFmay notify the first network element (e.g., the NEF/NIMF) that the PDUsession establishment is successful and may send the identifier of theUPF network element, an identifier of the PDU session for delivery ofthe one or more packets, and/or the like to the first network element.The first network element, upon receiving the notification of successfulPDU session establishment (e.g., comprising the identifier of the UPFnetwork element, the identifier of the PDU session, and/or the like),may send the one or more packets to the UPF network element.

In an example, a first network element may receive from a second networkelement, a first request message for delivery of one or more packets toa wireless device. The first request message may comprise the one ormore packets, an identifier for the wireless device, and/or the like.

In an example, the first network element may send to a networkrepository function (NRF), a first message indicating a request of a UPFnetwork element selection for a cellular internet-of-things (CIoT)packet transmission. The first message may comprise at least one of anidentifier of the first network element, a first single network sliceselection assistance information (S-NSSAI) associated with the CIoTpacket transmission, a PDU session type associated with the CIoT packettransmission, and/or the like.

In an example, the first network element may receive from the NRF inresponse to the first message, a second message. The second message maycomprise at least one of an identifier of a UPF network element, anaddress of the UPF network element, a second S-NSSAI that the UPFnetwork element supports, and/or the like.

In an example, the first network element may send to the UPF networkelement, a third message based on the second message. The third maymessage comprise the identifier of the first network element, the one ormore packets, the identifier for the wireless device, and/or the like.

In an example, the first message may further comprise a network functiontype of a UPF network element.

In an example, the first S-NSSAI may be the second S-NSSAI.

In an example, the UPF network element may send to a session managementfunction (SMF) network element, a data notification indicating anarrival of packets for the wireless device.

In an example, the NRF may receive from the UPF network element, a sixthmessage indicating that the UPF network element supports the CIoT packettransmission. The sixth message may comprise at least one of a networkfunction profile of the UPF network element, an identifier of the UPFnetwork element, the second S-NSSAI that the UPF network elementsupports, and/or the like.

In an example, the sending, by the first network element, the firstmessage may be in response to receiving a request for transmission ofone or more packets, the first network element requires to select a UPFsupporting CIoT, and/or the like.

In an example, the first network element may be a network exposurefunction (NEF).

In an example, the first network element may be a messaging function.

In an example, the messaging function may be a network IoT messagingfunction (NIMF).

In an example, the second network element may be a service capabilityserver (SCS), application server, application function, and/or the like.

In an example, the NRF, may select the UPF network element based on theelements of the first message.

In an example, the first network element, may select the UPF networkelement based on the elements of the first message and/or the secondmessage.

The method of claim 1, further comprising:

In an example, the UPF network element may buffer the one or morepackets.

In an example, the UPF network element, may send the data notificationto the SMF network element.

In an example, a first network element may receive from a second networkelement, a first request message for delivery of one or more packets toa wireless device. The first request message may comprise the one ormore packet, an identifier for the wireless device, and/or the like.

In an example, the first network element may send to a networkrepository function (NRF), a first message indicating a request of theUPF network element selection for a cellular internet-of-things (CIoT)packet transmission. The first message may comprise at least one of anidentifier of the first network element, a first single network sliceselection assistance information (S-NSSAI) associated with the CIoTpacket transmission, a PDU session type associated with the CIoT packettransmission, and/or the like.

In an example, the first network element may receive from the NRF inresponse to the first message, a second message. The second message maycomprise at least one of an identifier of a UPF network element, anaddress of the UPF network element, a second S-NSSAI that the UPFnetwork element supports, and/or the like.

In an example, first network element may buffer the one or more packets;

In an example, the first network element may send to the UPF networkelement, a fourth message indicating a data notification for thewireless device. The fourth message may comprise at least one of theidentifier of the first network element, the identifier for the wirelessdevice, and/or the like.

In an example, the UPF network element may send, in response toreceiving the fourth message, the data notification to the SMF networkelement.

In an example, the first message may further comprise a network functiontype of a UPF network element.

In an example, the first S-NSSAI may be the second S-NSSAI.

In an example, the UPF network element may send to a session managementfunction (SMF) network element, a data notification indicating anarrival of packets for the wireless device.

In an example, the NRF may receive from the UPF network element, a sixthmessage indicating that the UPF network element may support a CIoTpacket transmission. The sixth message may comprise at least one of anetwork function profile of the UPF network element, an identifier ofthe UPF network element, the second S-NSSAI that the UPF network elementsupports, and/or the like.

In an example, the first network element, may send the first message isin response to receiving a request for transmission of one or morepackets, when the first network element may be required to select a UPFsupporting CIoT, and/or the like.

In an example, the first network element, may determine that the UPFnetwork element requires CIoT packet transmission capability.

In an example, the first network element may be a network exposurefunction (NEF).

In an example, the first network element may be a messaging function.

In an example, the messaging function may be a network IoT messagingfunction (NIMF).

In an example, the second network element may be a service capabilityserver (SCS).

In an example, the second network element may be an application server(AS).

In an example, the second network element may be an application function(AF).

In an example, the NRF, may select the UPF network element based on theelements of the first message.

In an example, the first network element, may select the UPF networkelement based on the elements of the first message and the secondmessage.

In an example, a first network element may receive from a second networkelement, a first request message for delivery of one or more packets toa wireless device. The first request message may comprise the one ormore packets, an identifier for the wireless device, and/or the like.

In an example, the first network element may send to a networkrepository function (NRF), a ninth message indicating a request of theSMF network element selection for a cellular internet-of-things (CIoT)packet transmission. The ninth message may comprise at least one of anidentifier of the first network element, a first single network sliceselection assistance information (S-NSSAI) associated with the CIoTpacket transmission, a PDU session type associated with the CIoT packettransmission, and/or the like.

In an example, the first network element may receive, from the NRF inresponse to the ninth message, a tenth message. The tenth message maycomprise at least one of an identifier of a SMF network element, anaddress of the SMF network element, a second S-NSSAI that the SMFnetwork element supports, and/or the like.

In an example, the first network element, may buffer the one or morepackets.

In an example, the first network element may send to the SMF networkelement, an eleventh message indicating a data notification for thewireless device. The eleventh message may comprise at least one of theidentifier of the first network element, the identifier for the wirelessdevice, and/or the like.

In an example, the SMF network element, may select a UPF networkelement.

In an example, the SMF network element may send to the first networkelement, a seventh message indicating a data notificationacknowledgment. The seventh message may comprise at least one of anidentifier of a UPF network element, an address of the UPF networkelement, a second S-NSSAI that the UPF network element supports, and/orthe like.

In an example, the first network element may send to the UPF networkelement, an eighth message based on the elements of the seventh message.The eighth message may comprise the one or more packets, the identifierfor the wireless device, and/or the like.

In an example, the ninth message may further comprise a network functiontype of a SMF network element.

In an example, the first S-NSSAI may be the second S-NSSAI.

In an example, the UPF network element may send to a session managementfunction (SMF) network element, a data notification indicating anarrival of packets for the wireless device.

In an example, the NRF may receive from the UPF network element, a sixthmessage indicating that the UPF network element supports a CIoT packettransmission. The sixth message may comprise at least one of a networkfunction profile of the UPF network element, an identifier of the UPFnetwork element, the second S-NSSAI that the UPF network elementsupports, and/or the like.

In an example, the first network element, may send the ninth message inresponse to receiving a request for transmission of one or more packets,when the first network element requires to select a UPF supporting CIoT,and/or the like.

In an example, the SMF network element, may determine that the UPFnetwork element requires CIoT packet transmission capability.

In an example, the first network element may be a network exposurefunction (NEF).

In an example, the first network element may be a messaging function.

In an example, the messaging function may be a network IoT messagingfunction (NIMF).

In an example, the second network element may be a service capabilityserver (SCS), an application server (AS), an application function (AF),and/or the like.

In an example, the NRF, may select the SMF network element based on theelements of the ninth message.

In an example, the first network element, may select the SMF networkelement based on the elements of the ninth message and the tenthmessage.

In this specification, a and an and similar phrases are to beinterpreted as at least one and one or more. In this specification, theterm may is to be interpreted as may, for example. In other words, theterm may is indicative that the phrase following the term may is anexample of one of a multitude of suitable possibilities that may, or maynot, be employed to one or more of the various embodiments. If A and Bare sets and every element of A is also an element of B, A is called asubset of B. In this specification, only non-empty sets and subsets areconsidered. For example, possible subsets of B={cell1, cell2} are:{cell1}, {cell2}, and {cell1, cell2}.

In this specification, parameters (Information elements: IEs) maycomprise one or more objects, and each of those objects may comprise oneor more other objects. For example, if parameter (IE) N comprisesparameter (IE) M, and parameter (IE) M comprises parameter (IE) K, andparameter (IE) K comprises parameter (information element) J, then, forexample, N comprises K, and N comprises J. In an example embodiment,when one or more messages comprise a plurality of parameters, it impliesthat a parameter in the plurality of parameters is in at least one ofthe one or more messages, but does not have to be in each of the one ormore messages.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an isolatableelement that performs a defined function and has a defined interface toother elements. The modules described in this disclosure may beimplemented in hardware, software in combination with hardware,firmware, wetware (i.e. hardware with a biological element) or acombination thereof, which may be behaviorally equivalent. For example,modules may be implemented as a software routine written in a computerlanguage configured to be executed by a hardware machine (such as C,C++, Fortran, Java, Basic, Matlab or the like) or a modeling/simulationprogram such as Simulink, Stateflow, GNU Octave, or LabVIEWMathScript.Additionally, it may be possible to implement modules using physicalhardware that incorporates discrete or programmable analog, digitaland/or quantum hardware. Examples of programmable hardware comprise:computers, microcontrollers, microprocessors, application-specificintegrated circuits (ASICs); field programmable gate arrays (FPGAs); andcomplex programmable logic devices (CPLDs). Computers, microcontrollersand microprocessors are programmed using languages such as assembly, C,C++ or the like. FPGAs, ASICs and CPLDs are often programmed usinghardware description languages (HDL) such as VHSIC hardware descriptionlanguage (VHDL) or Verilog that configure connections between internalhardware modules with lesser functionality on a programmable device.Finally, it needs to be emphasized that the above mentioned technologiesare often employed in combination to achieve the result of a functionalmodule.

Example embodiments of the invention may be implemented using variousphysical and/or virtual network elements, software defined networking,virtual network functions.

The disclosure of this patent document incorporates material which issubject to copyright protection. The copyright owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and Trademark Officepatent file or records, for the limited purposes required by law, butotherwise reserves all copyright rights whatsoever.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example, and notlimitation. It will be apparent to persons skilled in the relevantart(s) that various changes in form and detail can be made thereinwithout departing from the spirit and scope. In fact, after reading theabove description, it will be apparent to one skilled in the relevantart(s) how to implement alternative embodiments. Thus, the presentembodiments should not be limited by any of the above describedexemplary embodiments. In particular, it should be noted that, forexample purposes, the above explanation has focused on the example(s)using 5G AN. However, one skilled in the art will recognize thatembodiments of the invention may also be implemented in a systemcomprising one or more legacy systems or LTE. The disclosed methods andsystems may be implemented in wireless or wireline systems. The featuresof various embodiments presented in this invention may be combined. Oneor many features (method or system) of one embodiment may be implementedin other embodiments. A limited number of example combinations are shownto indicate to one skilled in the art the possibility of features thatmay be combined in various embodiments to create enhanced transmissionand reception systems and methods.

In addition, it should be understood that any figures which highlightthe functionality and advantages, are presented for example purposes.The disclosed architecture is sufficiently flexible and configurable,such that it may be utilized in ways other than that shown. For example,the actions listed in any flowchart may be re-ordered or optionally usedin some embodiments.

Further, the purpose of the Abstract of the Disclosure is to enable theU.S. Patent and Trademark Office and the public generally, andespecially the scientists, engineers and practitioners in the art whoare not familiar with patent or legal terms or phraseology, to determinequickly from a cursory inspection the nature and essence of thetechnical disclosure of the application. The Abstract of the Disclosureis not intended to be limiting as to the scope in any way.

Finally, it is the applicant's intent that only claims that include theexpress language means for or step for be interpreted under 35 U.S.C.112. Claims that do not expressly include the phrase means for or stepfor are not to be interpreted under 35 U.S.C. 112.

What is claimed is:
 1. A method comprising: receiving, by a networkexposure function from an application function, a first messagerequesting delivery of one or more Internet of Things (IoT) packets to awireless device; sending, by the network exposure function to a networkrepository function, a second message requesting a discovery of a userplane function that supports cellular IoT optimization; receiving, bythe network exposure function from the network repository function, athird message comprising an identifier of the user plane function thatsupports the cellular IoT optimization; and sending, by the networkexposure function to the user plane function, a fourth messagerequesting delivery of the one or more IoT packets to the wirelessdevice.
 2. The method of claim 1, wherein the one or more IoT packetsare cellular IoT packets.
 3. The method of claim 1, wherein the firstmessage further comprises: an identifier of the wireless device; and theone or more IoT packets.
 4. The method of claim 1, wherein the firstmessage is a non-IP data delivery (NIDD) request.
 5. The method of claim1, wherein the second message further comprises a single network sliceselection assistance information (S-NSSAI) of the network exposurefunction.
 6. The method of claim 1, wherein the third message furthercomprises: an address of the user plane function that supports deliveryof the one or more IoT packets; and one or more single network sliceselection assistance information (S-NSSAIs) associated with the userplane function that supports the delivery of the one or more IoTpackets.
 7. The method of claim 1, further comprising buffering, by thenetwork exposure function, the one or more IoT packets.
 8. The method ofclaim 1, wherein the fourth message is a data notification message. 9.The method of claim 1, further comprising sending, by the networkexposure function to a session management function (SMF), a datanotification for the wireless device.
 10. The method of claim 1, furthercomprising sending, by the network exposure function to the user planefunction (UPF), the one or more IoT packets.
 11. A network exposurefunction comprising: one or more processors; and memory storinginstructions that, when executed by the one or more processors, causethe network exposure function to: receive from an application function,a first message requesting delivery of one or more Internet of Things(IoT) packets to a wireless device; send to a network repositoryfunction, a second message requesting a discovery of a user planefunction that supports cellular IoT optimization; receive from thenetwork repository function, a third message comprising an identifier ofthe user plane function that supports the cellular IoT optimization; andsend to the user plane function, a fourth message requesting delivery ofthe one or more IoT packets to the wireless device.
 12. The networkexposure function of claim 11, wherein the one or more IoT packets arecellular IoT packets.
 13. The network exposure function of claim 11,wherein the first message further comprises: an identifier of thewireless device; and the one or more IoT packets.
 14. The networkexposure function of claim 11, wherein the second message furthercomprises a single network slice selection assistance information(S-NSSAI) of the network exposure function.
 15. The network exposurefunction of claim 11, wherein the third message further comprises: anaddress of the user plane function that supports delivery of the one ormore IoT packets; and one or more single network slice selectionassistance information (S-NSSAIs) associated with the user planefunction that supports the delivery of the one or more IoT packets. 16.The network exposure function of claim 11, further comprising buffering,by the network exposure function, the one or more IoT packets.
 17. Thenetwork exposure function of claim 11, wherein the fourth message is adata notification message.
 18. The network exposure function of claim11, further comprising sending, by the network exposure function to asession management function (SMF), a data notification for the wirelessdevice.
 19. The network exposure function of claim 11, furthercomprising sending, by the network exposure function to the user planefunction (UPF), the one or more IoT packets.
 20. A system comprising: anetwork exposure function comprising: one or more first processors; andfirst memory storing first instructions that, when executed by the oneor more first processors, cause the network exposure function to receivefrom an application function, a first message requesting delivery of oneor more Internet of Things (IoT) packets to a wireless device; send to anetwork repository function, a second message requesting a discovery ofa user plane function that supports cellular IoT optimization; receivefrom the network repository function, a third message comprising anidentifier of the user plane function that supports the cellular IoToptimization; and send to the user plane function, a fourth messagerequesting delivery of the one or more IoT packets to the wirelessdevice; a network repository function comprising: one or more secondprocessors; and memory storing second instructions that, when executedby the one or more second processors, cause the network repositoryfunction to: receive from the network exposure function, the secondmessage; and send to the network exposure function, the third message;and a user plane function comprising: one or more third processors; andmemory storing third instructions that, when executed by the one or morethird processors, cause the user plane function to receive the fourthmessage.